From: Gavin Sinclair <gsinclair@...>
Date: 2004-11-14T01:20:49+09:00
Subject: Re: assert

On Sunday, November 14, 2004, 2:48:24 AM, Florian wrote:

> Gavin Sinclair wrote:

>>>>>I have thought about changing the name to "assume" so it can be included
>>>>>in dev-utils, but I'm not sure if that name is better.
>>>I think that would be way too much magic. I'd expect the method to just
>>>take a block.
>> 
>> Why a block?  The breakpoint code uses Binding.of_caller anyway, so a
>> block is not needed for evaluation.  I don't see any other reason,
>> technical or stylistic, why a block should be preferred.

> Using strings for code is a bit ugly. We have blocks in Ruby, why not
> use them? Using a String also causes a bit of escaping trouble (I know
> this can be worked around via the %{} or <<-END syntax, but I still 
> think blocks are clearer than that.)

Agreed, but you can print strings.  You can't print blocks.  See
below.

>> I suppose we might as well dispose of the symbolic argument and just
>> do this:
>> 
>>   breakpoint_unless 'x + y == 10'

> Why don't just use "breakpoint unless x + y == 10" then? I think it 
> makes sense to use something more concise here.

That option is still available.  breakpoint_unless 'x + y == 10' has
the added benefit that the breakpoint can be identified by the
condition that triggered it.  E.g. you run the program and see on the
console:

  Breakpoint because 'x + y == 10' is false.
  irb>

Is that a convincing benefit?

>> Can you expand on the "too much magic"?

> I don't know -- the syntax just seemed so very unnatural. Like something
> you wouldn't meet anywhere in the standard library...

Debugging code often stands out in this unfortunate way, though.  It's
lower level than normal code.

Now let me ask you: since you proposed

  assume { x + y == 10 }

what does that provide over

  breakpoint unless x + y == 10

?

Gavin