Using buffer may require even more editing than file , if your file has static PyMethodDef arrays defined in the middle of the file. Similar to the buffer preset, but writes forward declarations to the two-pass buffer, and definitions to the buffer. This is similar to the buffer preset, but may require less editing than buffer. Dump the two-pass buffer near the top of your file, and dump the buffer near the end just like you would when using the buffer preset.
Similar to the buffer preset, but writes more things to block , only writing the really big chunks of generated code to buffer. Dump the buffer near the end, just like you would when using the buffer preset. The third new directive is destination :. This performs an operation on the destination named name. There are two defined subcommands: new and clear. A text file. The file destination takes an extra argument, a template to use for building the filename, like so:.
It removes all the accumulated text up to this point in the destination. This tells Clinic that the current contents of the output should be kept, unmodifed. This is used internally by Clinic when dumping output into file files; wrapping it in a Clinic block lets Clinic use its existing checksum functionality to ensure the file was not modified by hand before it gets overwritten.
The existing code probably looks like this:. And then in the PyMethodDef structure at the bottom the existing code will have:. In this scenario, you should enclose the body of your impl function inside the ifdef , like so:.
Then, remove those three lines from the PyMethodDef structure, replacing them with the macro Argument Clinic generated:. You can find the real name for this macro inside the generated code. It actually detects that the Argument Clinic block might be deactivated by the ifdef. When that happens, it generates a little extra code that looks like this:.
That means the macro always works. If the function is defined, this turns into the correct structure, including the trailing comma. If the function is undefined, this turns into nothing. This may mean that you get a complaint from Argument Clinic:.
Since Python comments are different from C comments, Argument Clinic blocks embedded in Python files look slightly different. They look like this:. An introduction to the ipaddress module. Python Frequently Asked Questions. Enter search terms or a module, class or function name. Navigation index modules next previous Python » 3. Currently the following are explicitly supported: Numeric constants integer and float String constants True , False , and None Simple symbolic constants like sys.
A couple reasons: The proper converters are far easier to read and clearer in their intent. See the section on default values for how to use this. Specified as a string. Not currently supported, because PEP 8 mandates that the Python library may not use annotations.
The native integer value of this Python argument will be written to the parameter without any range checking, even for negative values. Requires that the Python value be a subclass of a Python type, as expressed in C. Specifies the C type that will be used to declare the variable. This is not a general-purpose facility; as a rule it only supports specific lists of types as shown in the legacy converter table. Or the magic value unspecified if there is no default.
Or None if there is no default. This value should always be a non-empty string. No PyMethodDef define is generated for these functions. Use the docstring as the class docstring.
This is what Clinic originally did. If the basename does not contain a period, this will be the empty string. The Python Software Foundation is a non-profit corporation. Please donate. Last updated on Sep 01, Found a bug? Approach 4 is good, but if you document your function as taking a bool, you are not obligated to accept just any object. Explicit type checks as in 3 without a reason are frowned upon in Python.
Conversion to another Python object as in 2 does not help your C code. From Python 3. Stack Overflow for Teams — Collaborate and share knowledge with a private group.
Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. What is the "correct" way to pass a boolean to a Python C extension? Ask Question. Asked 9 years, 11 months ago. Active 4 years, 3 months ago. I'd be happy to add such a test, but I don't know of any types like that.
Can anyone suggest one? This made me have to handle errors a little differently, so it was definitely good to test it. Thanks for the suggestion, Martin! Also changed wording in documentation ever-so-slightly. My name is Serhiy. In the end, bool subclasses int. But we have no middlecase for latin 'P'. Thanks for the feedback, Serhiy and Mark! In my defense it was rather late. Why you should use 'P' in the first place? Certainly one of the two expressions is! This was always a dumb idea, as the Some savings!
I've opted for the last of those. I considered briefly trying to make 'P' handle subclasses of bool. But then I hit the problem of: okay, what now? Anyway, what lunatic would subclass bool? I'm really on the fence about 'P'. Serhiy is definitely pro-, everyone else seems to think it shouldn't be used. However nobody has argued against its inclusion. At the moment I'm -0 on it myself, but since the code is written Do we have an anti-champion?
At any rate, it can be almost trivially imitated with "O! And we can use DefaultArg like this:. Python Extension Patterns latest. Introduction 2. PyObjects and Reference Counting 3. Exception Raising 4. Parsing Python Arguments 5. No Arguments 5. One Argument 5. Arguments as Borrowed References 5. Variable Number of Arguments 5. Variable Number of Arguments and Keyword Arguments 5. Being Pythonic with Default Arguments 5.
Simplifying Macros 5. Creating New Types 7. Setting and Getting Module Globals 8. Calling super from C 9.
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