How Guietta works

For the constructor aruguments:

  • argument checks (layer_check())
    1. Check that all elements are iterables, raise ValueError if not.
    2. Take the longest
    3. Expand single-elements ones to the longest using ___
    4. Check that all rows have the same length, raise ValueError if not.
  • Compact syntax is expanded (convert_compacts())
    1. ‘xxx’ is converted to L(‘xxx’)
    2. ‘__xxx__’ is converted to QLineEdit(‘xxx’)
    3. [‘xxx’, ‘yyy’] is converted to B(‘xxx’, ‘yyy’), with ‘yyy’ optional. Lists with 0 or >2 elements raise ValueError
    4. 2-tuples are recursed into in order to expand the first element if needed
  • Labels and buttons are created (create_deferred())

    • Labels
      1. L(‘xxx’) becomes (QLabel(‘xxx’), ‘xxx’)
      2. L(‘xxx.png’) becomes (QLabel(QPixmap(‘xxx.png’)), ‘xxx’)
    • Buttons
      1. B(‘xxx’) becomes (QPushButton(‘xxx’), ‘xxx’)
      2. B(‘xxx.png’, ‘yyy’ becomes (QPushButton(QIcon(‘xxx.png’)), ‘yyy’)
    • Automatic buttons (Quit, Yes, No.. etc) are created and connected
    • Separators are created
    • 2-tuples are rercursed into in order to expand the first element if needed.
  • Multiple names are collapsed (collapse_names())
    • Things like (((widget, ‘name1’), ‘name2’), ‘name3’) become (widget, ‘name3’). Nesting is flattened for an arbitrary depth.
  • Type check (check_widget()). All resulting widgets must be one of two types:
    1. A QWidget instance, or
    2. a 2-tuple (QWidget, ‘name’)

Instance properties

Widgets values can be get/set like a property:

gui.label = 'text'
value = gui.slider

These property-like attributes are created on the fly when the GUI is built. We cannot use real properties, because these are class attributes and they would be shared between instances. Instead, there is a dictionary self._guietta_properties which contains a mapping from property name to a pair of get/set functions (a namedtuple is used for the pair in order to have nice methods names). These methods are set to the ones appropriate for the widget type at construction time.

The _guietta_properties dict is used by __getattr__ and __setattr__ to emulate the property behaviour. Since these methods would be used to lookup _guietta_properties itself, this mapping must be created in the __init__ method as its first instruction, and using self.__dict__ instead of direct attribute access.