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POC nested switches: outer switch's case inside inner switch
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  1. POC nested switches: outer switch's case inside inner switch
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    copied!<p>I'm adding coroutine support to an interpreter I'm writing and I'd like to do something like the following:</p> <pre><code>typedef enum { bar_stuff, bar_other } Bar; typedef enum { foo_error=-1, foo_none=0, foo_again } Foo_state; Foo_state do_foo(Bar bar,Foo_state foo) { switch(foo) { case foo_none: //start switch(bar) { case bar_stuff: //do stuff return foo_none; case bar_other: //do other stuff return foo_again; case foo_again: //!! this doesn't work /* edit: this is supposed to be a case of * switch(foo), not switch(bar) */ //do more other stuff return foo_none; default: //stuff return foo_none; } default: //fail return foo_error; } } </code></pre> <p>Obviously this dosn't work (I get duplicate case value, alternative is probably undefined behavior/segfault). I could write switch(bar) as an if/else if/else chain, but I was hoping there was a better way.</p> <p>I'm using gcc if that makes a difference.</p> <h3>Edit:</h3> <p>The following would work, but would be a PITA to maintain:</p> <pre><code>Foo_state do_foo2(Bar bar,Foo_state foo) { switch(foo) { case foo_none: goto case_foo_none; case foo_again: goto case_foo_again; default: //fail return foo_error; } case_foo_none: //start switch(bar) { case bar_stuff: //do stuff return foo_none; case bar_other: //do other stuff return foo_again; case_foo_again: //do more other stuff return foo_none; default: //stuff return foo_none; } } </code></pre> <h3>Edit 2:</h3> <p>Well, this doesn't seem to be yielding the aforementioned 'better way', so I'd like know if anyone foresees a problem with writing it like this:</p> <pre><code>Foo_state do_foo3(Bar bar,Foo_state foo) { switch(foo) { case foo_none: //start if(bar == bar_stuff) { printf("do stuff\n"); return foo_none; } else if(bar == bar_other) { printf("do other stuff\n"); return foo_again; case foo_again: //continue printf("do more other stuff\n"); return foo_none; } else { printf("stuff\n"); return foo_none; } default: //fail return foo_error; } } </code></pre> <p>The problem I see with this is missing a bar_* value (since there are several functions like this, and some of the enums have dozens of values), but I suppose a test script for that should work...</p>
 

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