3 ms·

Any Python users willing to some feedback on some language ideas I had? Thanks

6 points by pwmanagerdied 17y ago

makecheck 17y ago
I'm not sure the block syntax buys as much as you'd want it to. Maybe a more complex example would help? For instance, you can create similar syntax with a class definition. I've tossed together something quick below to emulate your UI library (not really something I've tried in practice, but the idea is there): class ExampleLabel: caption = "This is an example" position = (50, 50) class ClickMeButton: caption = "Click me! Click me!" on_click = lambda: sys.stdout.write("The button was clicked.\n") class HelloWorldWindow: caption = "Hello World" dimensions = (400, 300) contains = (ExampleLabel, ClickMeButton) If you then had classes or functions with kwargs arguments, that recognized key names such as "caption", "on_click", etc., then the above classes could be used in this way to instantiate things (either alone, or within something like a Window): b = Button(**ClickMeButton.__dict__) l = Label(**ExampleLabel.__dict__) ...or equivalently, on the fly: l = Label(caption="Other label", position=(10, 20)) Notice that since everything is defined as a class, instantiating duplicates is actually taken care of. For example: w1 = Window(**HelloWorldWindow.__dict__) w2 = Window(**HelloWorldWindow.__dict__) Since I haven't "inlined" anything in a block assignment, the definition can be used repeatedly (when put in a class).
- pwmanagerdied 17y ago
  Thank you very much for the feedback. I tried to keep the examples simple so that the functionality was clear, I'll try to come up with a more concrete example to demonstrate it's utility. I'm aware that you can achieve a a lot of already using classes (and metaclasses), but I thought a clearer syntax would be helpful. I don't seeing my code cluttered with "class" when that's not what's actually happening, but of course that could be exactly what was happening in my example. One thing I originally had in my example (though I decided it wasn't a good idea so I removed it) was ui.on_event "click", "altclick": print("I've been clicked!") where on_event macro takes the paren-less tuple of event names and returns another macro which takes the block, then does the correct assignment. I realize this also isn't a strong example, but it's a little bit more than I have in the post.
- pwmanagerdied 17y ago
  Trying again: With this, it would be possible for a user to create a switch/case statement of their own. n = 3 switch n: case 1: print("n is one") case 2: print("n is two") default: print("n is neither one or two") by injecting "case" into the namespace of a block in "switch", we'd only have to add one identifier to the global namespace. Here's what some of the implementation code might look like. @macro def switch(value): @macro def _switch(block): cases = dict() def line_callback(value): if isinstance(value, SwitchCase): cases[SwitchCase.value] = SwithCase.block elif isinstance(value, DefaultCase): default = DefaultCase.block block(line_callback=line_callback) try: result_block = cases[value] except KeyError: result_block = default return(result_block()) return(_switch) I wasn't thinking of it exclusively as a data structure tool, but also possibly as a way to create your own flow control operations and such. This might not be the most compelling possible example in the world, but I hope it helps.

6 points by pwmanagerdied 17y ago

I'm not sure the block syntax buys as much as you'd want it to. Maybe a more complex example would help? For instance, you can create similar syntax with a class definition. I've tossed together something quick below to emulate your UI library (not really something I've tried in practice, but the idea is there): class ExampleLabel: caption = "This is an example" position = (50, 50) class ClickMeButton: caption = "Click me! Click me!" on_click = lambda: sys.stdout.write("The button was clicked.\n") class HelloWorldWindow: caption = "Hello World" dimensions = (400, 300) contains = (ExampleLabel, ClickMeButton) If you then had classes or functions with kwargs arguments, that recognized key names such as "caption", "on_click", etc., then the above classes could be used in this way to instantiate things (either alone, or within something like a Window): b = Button(**ClickMeButton.__dict__) l = Label(**ExampleLabel.__dict__) ...or equivalently, on the fly: l = Label(caption="Other label", position=(10, 20)) Notice that since everything is defined as a class, instantiating duplicates is actually taken care of. For example: w1 = Window(**HelloWorldWindow.__dict__) w2 = Window(**HelloWorldWindow.__dict__) Since I haven't "inlined" anything in a block assignment, the definition can be used repeatedly (when put in a class).

pwmanagerdied 17y ago
Thank you very much for the feedback. I tried to keep the examples simple so that the functionality was clear, I'll try to come up with a more concrete example to demonstrate it's utility. I'm aware that you can achieve a a lot of already using classes (and metaclasses), but I thought a clearer syntax would be helpful. I don't seeing my code cluttered with "class" when that's not what's actually happening, but of course that could be exactly what was happening in my example. One thing I originally had in my example (though I decided it wasn't a good idea so I removed it) was ui.on_event "click", "altclick": print("I've been clicked!") where on_event macro takes the paren-less tuple of event names and returns another macro which takes the block, then does the correct assignment. I realize this also isn't a strong example, but it's a little bit more than I have in the post.
pwmanagerdied 17y ago
Trying again: With this, it would be possible for a user to create a switch/case statement of their own. n = 3 switch n: case 1: print("n is one") case 2: print("n is two") default: print("n is neither one or two") by injecting "case" into the namespace of a block in "switch", we'd only have to add one identifier to the global namespace. Here's what some of the implementation code might look like. @macro def switch(value): @macro def _switch(block): cases = dict() def line_callback(value): if isinstance(value, SwitchCase): cases[SwitchCase.value] = SwithCase.block elif isinstance(value, DefaultCase): default = DefaultCase.block block(line_callback=line_callback) try: result_block = cases[value] except KeyError: result_block = default return(result_block()) return(_switch) I wasn't thinking of it exclusively as a data structure tool, but also possibly as a way to create your own flow control operations and such. This might not be the most compelling possible example in the world, but I hope it helps.