Since the beginning one of the PySide goals was to be API compatible with PyQt4, but with some (documented) exceptions. For example, PySide will not export to Python components marked as deprecated on C++ Qt. All the modifications follow the PSEP101 as its guideline.
The release 4.7 of PyQt4 came with improvements on the pythonic front, being the extinction of QString a good example. PySide followed this change, except in one point: while PyQt4 has conserved the old behavior as optional, PySide bindings fully adopted the new API - completely removing QString. No turning back. Thus remember to update your source code to the new API, this will ensure your code will run on both bindings.
The hash value returned for the classes PySide.QtCore.QDate, PySide.QtCore.QDateTime, PySide.QtCore.QTime, PySide.QtCore.QUrl will be based on their string representations, thus objects with the same value will produce the same hash.
Methods and functions that change the contents of a QString argument were modified to receive an immutable Python unicode (or str) and return another Python unicode/str as the modified string.
The following methods had their return types modified this way:
Classes: QAbstractSpinBox, QDateTimeEdit, QDoubleSpinBox, QSpinBox, QValidator
Classes: QDoubleValidator, QIntValidator, QRegExpValidator
Instead of getOpenFileNameAndFilter(), getOpenFileNamesAndFilter() and getSaveFileNameAndFilter() like PyQt4 does, PySide has modified the original methods to return a tuple.
Inside this class some renames were applied to avoid clashes with native Python functions. They are: bin_(), hex_() and oct_(). The only modification was the addition of ‘_’ character.
As QVariant was removed, any function expecting it can receive any Python object (None is an invalid QVariant). The same rule is valid when returning something: the returned QVariant will be converted to the its original Python object type.
When a method expects a QVariant::Type the programmer can use a string (the type name) or the type itself.