GeezerVisonThe World Wide Web, restored to 800 pixels of glory. |
| Home|About|Gaming cabinet|Archives|How it works|Starter sites |
GeezerVison is showing github.com — pythonnet/htdocs/readme.html at develop · achernet/pythonnet Expand file tree/ Copy pathreadme.htmlMore file actions executable file ·672 lines (630 loc) · 29.1 KB / Copy pathreadme.htmlFile metadata and controlsexecutable file ·672 lines (630 loc) · 29.1 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 <html> <head> <title>Python for .NET</title> <style type="text/css"><!-- body { font: 8pt/16pt georgia,verdana; text-decoration: none; color: #555753; background: #ffffff; margin: 0px; } p { font: 8pt/16pt georgia; } h1 { font: bold 14pt; color: #000044; /* background-color: #EFEFFF; color: #000044; border-style: solid; border-width: 1px; border-color: #555753; padding: 6px, 2px, 6px, 2px; */ } h2 { font: bold 14pt; margin-bottom: 0px; color: #000044; } h3 { font: bold 12pt; margin-bottom: 0px; color: #000044; } a:link { font-weight: bold; text-decoration: none; color: #000066; } a:visited { font-weight: bold; text-decoration: none; color: #000066; } a:hover, a:active { text-decoration: underline; color: #000066; } pre { font-family: monospace; background-color: #EFEFFF; color: #000044; border-style: solid; border-width: 1px; border-color: #555753; padding: 6px, 2px, 6px, 2px; } li { font: 8pt/16pt georgia,verdana; text-decoration: none; color: #555753; } .spacer { font: bold 14pt; } .menu { background-color: #EFEFFF; color: #000044; border-style: solid; border-width: 1px; border-color: #555753; padding: 6px, 2px, 6px, 2px; font-size: x-small; } .menu ul { margin: 0px; padding: 0px; } //--></style> <meta content="text/html; charset=ISO-8859-1" http-equiv="content-type"> </head> <body> <table border="0" cellspacing="4" width="98%"> <tbody> <tr> <td class="menu" align="left" valign="top" width="20%"> <h1>Python for .NET</h1> <ul> <li><a href="#installation">Installation</a></li> <li><a href="#getting_started">Getting Started</a></li> <li><a href="#importing">Importing Modules</a></li> <li><a href="#classes">Using Classes</a></li> <li><a href="#generics">Using Generics</a></li> <li><a href="#fields">Fields and Properties</a></li> <li><a href="#indexers">Using Indexers</a></li> <li><a href="#methods">Using Methods</a></li> <li><a href="#genericmethods">Overloaded and Generic Methods</a></li> <li><a href="#delegates">Delegates and Events</a></li> <li><a href="#exceptions">Exception Handling</a></li> <li><a href="#arrays">Using Arrays</a></li> <li><a href="#collections">Using Collections</a></li> <li><a href="#com">COM Components</a></li> <li><a href="#types">Type Conversion</a></li> <li><a href="#embedding">Embedding Python</a></li> <li><a href="#license">License</a></li> </ul> </td> <td align="left" valign="top"> <p> Python for .NET is a package that gives Python programmers nearly seamless integration with the .NET Common Language Runtime (CLR) and provides a powerful application scripting tool for .NET developers. Using this package you can script .NET applications or build entire applications in Python, using .NET services and components written in any language that targets the CLR (Managed C++, C#, VB, JScript). </p> <p> Note that this package does <em>not</em> implement Python as a first-class CLR language - it does not produce managed code (IL) from Python code. Rather, it is an integration of the C Python engine with the .NET runtime. This approach allows you to use use CLR services and continue to use existing Python code and C-based extensions while maintaining native execution speeds for Python code. If you are interested in a pure managed-code implementation of the Python language, you should check out the <a href="http://www.ironpython.com">IronPython</a> project, which is in active development. </p> <p> Python for .NET is currently compatible with Python releases 2.3 and greater. Current releases are available at the <a href="http://pythonnet.sourceforge.net/"> Python for .NET website </a>. To subscribe to the <a href="http://mail.python.org/mailman/listinfo/pythondotnet"> Python for .NET mailing list </a> or read the <a href="http://mail.python.org/pipermail/pythondotnet/"> online archives </a> of the list, see the <a href="http://mail.python.org/mailman/listinfo/pythondotnet"> mailing list information </a> page. </p> <a name="#installation"></a> <h2>Installation</h2> <p> Python for .NET is available as a source release and as a Windows installer for various versions of Python and the common language runtime from the <a href="http://pythonnet.sourceforge.net/"> Python for .NET website </a>. On Windows platforms, you can choose to install .NET-awareness into an existing Python installation as well as install Python for .NET as a standalone package. </p> <p> The source release is a self-contained "private" assembly. Just unzip the package wherever you want it, cd to that directory and run python.exe to start using it. Note that the source release does not include a copy of the CPython runtime, so you will need to have installed Python on your machine before using the source release. </p> <p> <strong>Running on Linux/Mono:</strong> preliminary testing shows that PythonNet will run under <a href="http://www.go-mono.com">Mono</a>, though the Mono runtime is not yet complete so there still may be problems. The Python for .NET integration layer is 100% managed code, so there should be no long-term issues under Mono - it should work better and better as the Mono platform matures. </p> <p> Note that if you are running under Mono on a *nix system, you will need to have a compatible version of Python installed. You will also need to create a symbolic link to the copy of libpython2.x.so (in your existing Python installation) in the PythonNet directory. This is needed to ensure that the mono interop dll loader will find it by name. For example: </p> <pre> ln -s /usr/lib/libpython2.4.so ./python24.so </pre> <a name="getting_started"></a> <h2>Getting Started</h2> <p> A key goal for this project has been that Python for .NET should "work just the way you'd expect in Python", except for cases that are .NET specific (in which case the goal is to work "just the way you'd expect in C#"). In addition, with the IronPython project gaining traction, it is my goal that code written for IronPython run without modification under Python for .NET. </p> <p> If you already know Python, you can probably finish this readme and then refer to .NET docs to figure out anything you need to do. Conversely if you are familiar with C# or another .NET language, you probably just need to pick up one of the many good Python books or read the Python tutorial online to get started. </p> <p> A good way to start is to run <strong>python.exe</strong> and follow along with the examples in this document. If you get stuck, there are also a number of demos and unit tests located in the source directory of the distribution that can be helpful as examples. </p> <p> Note that if you have installed CLR support into your existing Python installation (rather than using the included python.exe), you will need to use the line: "'import clr" (lower-case!) to initially load the clr extension module before trying the following examples. </p> <a name="importing"></a> <h2>Importing Modules</h2> <p> Python for .NET allows CLR namespaces to be treated essentially as Python packages. </p> <p> </p> <pre> from System import String from System.Collections import * </pre> <p> <em> Note that earlier releases of Python for .NET required you to import modules through a special top-level package named <code>CLR</code>. This is no longer required if you are starting python from the managed python.exe from this distribution.<br> <code>CLR</code> has been deprecated in favor of the more pythonic <code>clr</code>, though the syntax is still supported for backward compatibility. </em> </p> <p> Types from any loaded assembly may be imported and used in this manner. To load an assembly, use the "AddReference" function in the "clr" module: </p> <pre> import clr clr.AddReference("System.Windows.Forms") from System.Windows.Forms import Form </pre> <p> <em> Note that earlier releases of Python for .NET relied on "implicit loading" to support automatic loading of assemblies whose names corresponded to an imported namespace. Implicit loading still works for backward compatibility, but will be removed in a future release so it is recommended to use the clr.AddReference method. </em> </p> <p> Python for .NET uses the PYTHONPATH (sys.path) to look for assemblies to load, in addition to the usual application base and the GAC. To ensure that you can implicitly import an assembly, put the directory containing the assembly in <code>sys.path</code>. </p> <a name="classes"></a> <h2>Using Classes</h2> <p> Python for .NET allows you to use any non-private classes, structs, interfaces, enums or delegates from Python. To create an instance of a managed class, you use the standard instantiation syntax, passing a set of arguments that match one of its public constructors: </p> <pre> from System.Drawing import Point p = Point(5, 5) </pre> <p> In most cases, Python for .NET can determine the correct constructor to call automatically based on the arguments. In some cases, it may be necessary to call a particular overloaded constructor, which is supported by a special "__overloads__" attribute, which will soon be deprecated in favor of iPy compatible "Overloads", on a class: </p> <pre> from System import String, Char, Int32 s = String.Overloads[Char, Int32]('A', 10) s = String.__overloads__[Char, Int32]('A', 10) </pre> <a name="generics"></a> <h2>Using Generics</h2> <p> When running under versions of the .NET runtime greater than 2.0, you can use generic types. A generic type must be bound to create a concrete type before it can be instantiated. Generic types support the subscript syntax to create bound types: </p> <pre> from System.Collections.Generic import Dictionary from System import * dict1 = Dictionary[String, String]() dict2 = Dictionary[String, Int32]() dict3 = Dictionary[String, Type]() </pre> <p> When you pass a list of types using the subscript syntax, you can also pass a subset of Python types that directly correspond to .NET types: </p> <pre> dict1 = Dictionary[str, str]() dict2 = Dictionary[str, int]() dict3 = Dictionary[str, Decimal]() </pre> <p> This shorthand also works when explicitly selecting generic methods or specific versions of overloaded methods and constructors (explained later). </p> <p> You can also subclass managed classes in Python, though members of the Python subclass are not visible to .NET code. See the <code>helloform.py</code> file in the <code>/demo</code> directory of the distribution for a simple Windows Forms example that demonstrates subclassing a managed class. </p> <a name="fields"></a> <h2>Fields And Properties</h2> <p> You can get and set fields and properties of CLR objects just as if they were regular attributes: </p> <pre> from System import Environment name = Environment.MachineName Environment.ExitCode = 1 </pre> <a name="indexers"></a> <h2>Using Indexers</h2> <p> If a managed object implements one or more indexers, you can call the indexer using standard Python indexing syntax: </p> <pre> from System.Collections import Hashtable table = Hashtable() table["key 1"] = "value 1" </pre> <p> Overloaded indexers are supported, using the same notation one would use in C#: </p> <pre> items[0, 2] items[0, 2, 3] </pre> <a name="methods"></a> <h2>Using Methods</h2> <p> Methods of CLR objects behave generally like normal Python methods. Static methods may be called either through the class or through an instance of the class. All public and protected methods of CLR objects are accessible to Python: </p> <pre> from System import Environment drives = Environment.GetLogicalDrives() </pre> <p> It is also possible to call managed methods <code>unbound</code> (passing the instance as the first argument) just as with Python methods. This is most often used to explicitly call methods of a base class. </p> <p> <em>Note that there is one caveat related to calling unbound methods: it is possible for a managed class to declare a static method and an instance method with the same name. Since it is not possible for the runtime to know the intent when such a method is called unbound, the static method will always be called.</em> </p> <p> The docstring of CLR a method (__doc__) can be used to view the signature of the method, including overloads if the CLR method is overloaded. You can also use the Python <code>help</code> method to inspect a managed class: </p> <pre> from System import Environment print Environment.GetFolderPath.__doc__ help(Environment) </pre> <a name="genericmethods"></a> <h2>Overloaded and Generic Methods</h2> <p> While Python for .NET will generally be able to figure out the right version of an overloaded method to call automatically, there are cases where it is desirable to select a particular method overload explicitly. </p> <p> Methods of CLR objects have an "__overloads__", which will soon be deprecated in favor of iPy compatible Overloads, attribute that can be used for this purpose : </p> <pre> from System import Console Console.WriteLine.Overloads[bool](true) Console.WriteLine.Overloads[str]("true") Console.WriteLine.__overloads__[int](42) </pre> <p> Similarly, generic methods may be bound at runtime using the subscript syntax directly on the method: </p> <pre> someobject.SomeGenericMethod[int](10) someobject.SomeGenericMethod[str]("10") </pre> <a name="delegates"></a> <h2>Delegates And Events</h2> <p> Delegates defined in managed code can be implemented in Python. A delegate type can be instantiated and passed a callable Python object to get a delegate instance. The resulting delegate instance is a true managed delegate that will invoke the given Python callable when it is called: </p> <pre> def my_handler(source, args): print 'my_handler called!' # instantiate a delegate d = AssemblyLoadEventHandler(my_handler) # use it as an event handler AppDomain.CurrentDomain.AssemblyLoad += d </pre> <p> Multicast delegates can be implemented by adding more callable objects to a delegate instance: </p> <pre> d += self.method1 d += self.method2 d() </pre> <p> Events are treated as first-class objects in Python, and behave in many ways like methods. Python callbacks can be registered with event attributes, and an event can be called to fire the event. </p> <p> Note that events support a convenience spelling similar to that used in C#. You do not need to pass an explicitly instantiated delegate instance to an event (though you can if you want). Events support the <code>+=</code> and <code>-=</code> operators in a way very similar to the C# idiom: </p> <pre> def handler(source, args): print 'my_handler called!' # register event handler object.SomeEvent += handler # unregister event handler object.SomeEvent -= handler # fire the event result = object.SomeEvent(...) </pre> <a name="exceptions"></a> <h2>Exception Handling</h2> <p> You can raise and catch managed exceptions just the same as you would pure-Python exceptions: </p> <pre> from System import NullReferenceException try: raise NullReferenceException("aiieee!") except NullReferenceException, e: print e.Message print e.Source </pre> <p></p> <a name="arrays"></a> <h2>Using Arrays</h2> <p> The type <code>System.Array</code> supports the subscript syntax in order to make it easy to create managed arrays from Python: </p> <pre> from System import Array myarray = Array[int](10) </pre> <p> Managed arrays support the standard Python sequence protocols: </p> <pre> items = SomeObject.GetArray() # Get first item v = items[0] items[0] = v # Get last item v = items[-1] items[-1] = v # Get length l = len(items) # Containment test test = v in items </pre> <p> Multidimensional arrays support indexing using the same notation one would use in C#: </p> <pre> items[0, 2] items[0, 2, 3] </pre> <a name="collections"></a> <h2>Using Collections</h2> <p> Managed arrays and managed objects that implement the IEnumerable interface can be iterated over using the standard iteration Python idioms: </p> <pre> domain = System.AppDomain.CurrentDomain for item in domain.GetAssemblies(): name = item.GetName() </pre> <a name="com"></a> <h2>Using COM Components</h2> <p> Using Microsoft-provided tools such as <strong>aximp.exe</strong> and <strong>tlbimp.exe</strong>, it is possible to generate managed wrappers for COM libraries. After generating such a wrapper, you can use the libraries from Python just like any other managed code. </p> <p> Note: currently you need to put the generated wrappers in the GAC, in the PythonNet assembly directory or on the PYTHONPATH in order to load them. </p> <a name="types"></a> <h2>Type Conversion</h2> <p> Type conversion under Python for .NET is fairly straightforward - most elemental Python types (string, int, long, etc.) convert automatically to compatible managed equivalents (String, Int32, etc.) and vice-versa. Note that all strings returned from the CLR are returned as unicode. </p> <p> Types that do not have a logical equivalent in Python are exposed as instances of managed classes or structs (System.Decimal is an example). </p> <p> The .NET architecture makes a distinction between <code>value types</code> and <code>reference types</code>. Reference types are allocated on the heap, and value types are allocated either on the stack or in-line within an object. </p> <p> A process called <code>boxing</code> is used in .NET to allow code to treat a value type as if it were a reference type. Boxing causes a separate copy of the value type object to be created on the heap, which then has reference type semantics. </p> <p> Understanding boxing and the distinction between value types and reference types can be important when using Python for .NET because the Python language has no value type semantics or syntax - in Python "everything is a reference". </p> <p> Here is a simple example that demonstrates an issue. If you are an experienced C# programmer, you might write the following code: </p> <pre> items = System.Array.CreateInstance(Point, 3) for i in range(3): items[i] = Point(0, 0) items[0].X = 1 # won't work!! </pre> <p> While the spelling of <code>items[0].X = 1</code> is the same in C# and Python, there is an important and subtle semantic difference. In C# (and other compiled-to-IL languages), the compiler knows that Point is a value type and can do the Right Thing here, changing the value in place. </p> <p> In Python however, "everything's a reference", and there is really no spelling or semantic to allow it to do the right thing dynamically. The specific reason that <code>items[0]</code> itself doesn't change is that when you say <code>items[0]</code>, that getitem operation creates a Python object that holds a reference to the object at <code>items[0]</code> via a GCHandle. That causes a ValueType (like Point) to be boxed, so the following setattr (<code>.X = 1</code>) <em>changes the state of the boxed value, not the original unboxed value</em>. </p> <p> The rule in Python is essentially: "the result of any attribute or item access is a boxed value", and that can be important in how you approach your code. </p> <p> Because there are no value type semantics or syntax in Python, you may need to modify your approach. To revisit the previous example, we can ensure that the changes we want to make to an array item aren't "lost" by resetting an array member after making changes to it: </p> <pre> items = System.Array.CreateInstance(Point, 3) for i in range(3): items[i] = Point(0, 0) # This _will_ work. We get 'item' as a boxed copy of the Point # object actually stored in the array. After making our changes # we re-set the array item to update the bits in the array. item = items[0] item.X = 1 items[0] = item </pre> <p> This is not unlike some of the cases you can find in C# where you have to know about boxing behavior to avoid similar kinds of <code>lost update</code> problems (generally because an implicit boxing happened that was not taken into account in the code). </p> <p> This is the same thing, just the manifestation is a little different in Python. See the .NET documentation for more details on boxing and the differences between value types and reference types. </p> <a name="embedding"></a> <h2>Embedding Python</h2> <p> <strong>Note:</strong> because Python code running under Python for .NET is inherently unverifiable, it runs totally under the radar of the security infrastructure of the CLR so you should restrict use of the Python assembly to trusted code. </p> <p> The Python runtime assembly defines a number of public classes that provide a subset of the functionality provided by the Python C API. </p> <p> These classes include PyObject, PyList, PyDict, etc. The source and the unit tests are currently the only API documentation.. The rhythym is very similar to using Python C++ wrapper solutions such as CXX. </p> <p> At a very high level, to embed Python in your application you will need to: </p> <ul> <li>Reference Python.Runtime.dll in your build environment</li> <li>Call PythonEngine.Intialize() to initialize Python</li> <li>Call PythonEngine.ImportModule(name) to import a module</li> </ul> <p> The module you import can either start working with your managed app environment at the time its imported, or you can explicitly lookup and call objects in a module you import. </p> <p> For general-purpose information on embedding Python in applications, use www.python.org or Google to find (C) examples. Because Python for .NET is so closely integrated with the managed environment, you will generally be better off importing a module and deferring to Python code as early as possible rather than writing a lot of managed embedding code. </p> <p> <strong>Important Note for embedders:</strong> Python is not free-threaded and uses a global interpreter lock to allow multi-threaded applications to interact safely with the Python interpreter. Much more information about this is available in the Python C API documentation on the www.python.org Website. </p> <p> When embedding Python in a managed application, you have to manage the GIL in just the same way you would when embedding Python in a C or C++ application. </p> <p> Before interacting with any of the objects or APIs provided by the Python.Runtime namespace, calling code must have acquired the Python global interpreter lock by calling the <code>PythonEngine.AcquireLock</code> method. The only exception to this rule is the <code>PythonEngine.Initialize</code> method, which may be called at startup without having acquired the GIL. </p> <p> When finished using Python APIs, managed code must call a corresponding <code>PythonEngine.ReleaseLock</code> to release the GIL and allow other threads to use Python. </p> <p> The AcquireLock and ReleaseLock methods are thin wrappers over the unmanaged <code>PyGILState_Ensure</code> and <code>PyGILState_Release</code> functions from the Python API, and the documentation for those APIs applies to the managed versions. </p> <a name="license"> <h2>License</h2> </a> <p><a name="license"> Python for .NET is released under the open source Zope Public License (ZPL). A copy of the ZPL is included in the distribution, or you can find a copy of the </a><a href="http://pythonnet.sourceforge.net/license.txt"> ZPL online </a>. Some distributions of this package include a copy of the C Python dlls and standard library, which are covered by the <a href="http://www.python.org/license.html"> Python license </a>. </p> </td> </tr> </tbody> </table> </body> </html> |
| You are visitor 01402520 — GeezerVison does not store the pages you look up. Best viewed with Netscape Navigator 4.7 or Internet Explorer 6 at 800×600. No cookies required. |