Programming Python, 3rd Edition

GuiStreams: Redirecting Streams to Widgets

The script in Example 11-9 arranges to map input and output sources to pop-up windows in a GUI application, much as we did with strings in the stream redirection topics in Chapter 3. Although this module is really just a first-cut prototype and needs improvement itself (e.g., each input line request pops up a new input dialog), it demonstrates the concepts in general.

Its GuiOutput and GuiInput objects define methods that allow them to masquerade as files in any interface that expects a real file. As we learned earlier in Chapter 3, this includes standard stream processing tools, such as print and raw_input, and it includes explicit read and write calls. The two top-level interfaces in this module handle common use cases:

• The redirectedGuiFunc function uses this plug-and-play file compatibility to run a function with its standard input and output streams mapped completely to pop-up windows rather than to the console window (or wherever streams would otherwise be mapped in the system shell).

• The redirectedGuiShellCmd function similarly routes the output of a spawned shell command line to a pop-up window. It can be used to display the output of any program in a GUI—including that printed by a Python program.

The module’s GuiInput and GuiOutput classes can also be used or customized directly by clients that need more fine-grained control over the process.

Example 11-9. PP3E\Gui\Tools\guiStreams.py

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