Diffstat (limited to 'sources/shiboken2/libshiboken/signature_doc.rst')
1 files changed, 63 insertions, 19 deletions
diff --git a/sources/shiboken2/libshiboken/signature_doc.rst b/sources/shiboken2/libshiboken/signature_doc.rst
index f51649b5..9c42c597 100644
@@ -50,7 +50,7 @@ result of the ``__signature__`` attribute of the real ``PyCFunction`` object.
There is one thing that really changes Python a bit:
-* I added the ``__signature__`` attribute to every function.
+* We added the ``__signature__`` attribute to every function.
That is a little change to Python that does not harm, but it saves us
tons of code, that was needed in the early versions of the module.
@@ -59,9 +59,9 @@ The internal work is done in two steps:
* All functions of a class get the *signature text* when the module is imported.
This is only a very small overhead added to the startup time. It is a single
- string for the whole class.
+ string for each whole class.
* The actual signature object is created later, when the attribute is really
- accessed. Signatures are cached and only created on first access.
+ requested. Signatures are cached and only created on first access.
@@ -76,10 +76,12 @@ Why this Code is Fast
It costs a little time (maybe 4 seconds) to run througs every single signature
object, since these are more than 15000 Python objects. But all the signature
objects will be rarely accessed but in special applications.
-The normal case are only a few accesses, and these work pretty fast.
+The normal case are only a few accesses, and these are working pretty fast.
The key to make this signature module fast is to avoid computation as much as
-possible. When no signature objects are used, then no time is lost in initialization.
+possible. When no signature objects are used, then almost no time is lost in
+initialization. Only the above mentioned strings and some support modules are
+additionally loaded on ``import PySide2``.
When it comes to signature usage, then late initialization is used and cached.
This technique is also known as *full laziness* in haskell.
@@ -107,15 +109,27 @@ The C++ code involved with the signature module is completely in the file
shiboken2/libshiboken/signature.cpp . All other functionality is implemented in
the ``signature`` Python package. It has the following structure::
-Really important are the **parser**, **mapping** and **loader** modules. The rest is
-needed to create Python 2 compatibility.
+Really important are the **parser**, **mapping**, **errorhandler**, **enum_sig**,
+**layout** and **loader** modules. The rest is needed to create Python 2 compatibility
+or be compatible with embedding and installers.
@@ -143,6 +157,34 @@ needs. A lot of mappings are resolved by rather complex expressions in ``parser.
but a few hundred cases are better to spell explicitly, here.
+Since ``Qt For Python 5.12``, we no longer use the builtin type error messages from C++.
+Instead, we get much better results with the signature module. At the same time,
+this enforced supporting shiboken as well, and the signature module was no longer
+The diverse applications of the signature module all needed to iterate over modules,
+classes and functions. In order to centralize this enumeration, the process has
+been factored out as a context manager. The user has only to supply functions
+that do the actual formatting.
+See for example the .pyi generator ``pyside2/PySide2/support/generate_pyi.py``.
+As more applications used the signature module, different formatting of signatures
+was needed. To support that, we created the function ``create_signature``, which
+has a parameter to choose from some prefefined layouts.
@@ -276,19 +318,21 @@ This serves as an extra challenge that has a very positive effect on
the completeness and correctness of signatures.
Before the signature module was written, there already existed the concept of
-signatures, but in a more C++ - centric way. From that time, there still exist
+signatures, but in a more C++ - centric way. From that time, there existed
the error messages, which are created when a function gets wrong argument types.
-These error messages should be replaced by text generated on demand by
+These error messages were replaced by text generated on demand by
the signature module, in order to be more consistent and correct.
+This was implemented in ``Qt For Python 5.12.0``.
-Additionally, the ``__doc__`` attribute of PySide methods is not set, yet.
-It would be easy to get a nice ``help()`` feature by creating signatures
+Additionally, the ``__doc__`` attribute of PySide methods was not set.
+It was easy to get a nice ``help()`` feature by creating signatures
as default content for docstrings.
+This was implemented in ``Qt For Python 5.12.1``.