:DBG

[Pascal Costanza]

Hm, just when I thought this the mailing list for professional Common Lisp users.

Off the top of my hat: http://www.lispworks.com/documentation/HyperSpec/Body/11_abcb.htm

Pascal

Sent from my iPad

> On 18 Nov 2013, at 08:51, Hans Hübner <hans.huebner at gmail.com> wrote:
> 
> Pascal,
> 
> if you mean what you write, can you give some reasoning?
> 
> -Hans
> 
> 
> 2013/11/18 Pascal Costanza <pc at p-cos.net>
>> DON'T TOUCH THE KEYWORDS PACKAGE! Are you crazy?!?
>> 
>> This will be setting a very bad precedence. Just don't. Really!
>> 
>> Pascal
>> 
>> Sent from my iPad
>> 
>> > On 18 Nov 2013, at 06:17, Faré <fahree at gmail.com> wrote:
>> >
>> > In ASDF 3.1.0.14, I introduced a macro :DBG (in uiop/utility.lisp).
>> > Yes, it's in the keyword package. Why?
>> > Because it's the one and only macro I want to be accessible from everywhere
>> > without a prefix, yet without modifying existing defpackage forms to make
>> > it accessible — because it's only used temporarily for debugging.
>> >
>> > :DBG is a macro for print-debugging. The syntax is
>> >   (:DBG tag forms... last-form)
>> > The semantics is that if tag is true, print the tag, then for each
>> > form, write its source and its values; return the values of the last
>> > form. If tag is false, just evaluate the last form and return its
>> > values. (Tag is typically a constant keyword or string, identifying
>> > the point where values are printed.)
>> > The expansion is rather space and time efficient, as far as the
>> > semantics permit.
>> >
>> > I find :DBG soooo useful for print-debugging. I've seen tens of
>> > variants of it, but every time with something not quite right in the
>> > syntax, semantics or implementation. I just wanted one variant that
>> > got everything right, and make it ubiquitous. Because when you need
>> > it, you need it now, and there's no time to modify things to load an
>> > additional library. And when you're done, you want minimal cleanup,
>> > too: just delete the form, except maybe keep the last subform.
>> >
>> > Previously, I was using (uiop:uiop-debug) from uiop/utility which
>> > allows you to load a magic file of your choice that defines a debug
>> > mode. The default one I provided was mine, which define :DBG as DBG in
>> > your current package (thereby avoiding symbol import issues). But that
>> > still adds a new definition everytime and an extra line or form to
>> > cleanup.
>> >
>> > I was recently convinced that using the keyword package instead makes
>> > perfect sense: on the one hand, that's using a shared namespace that
>> > it is polite to not pollute, but on the other hand, such a temporary
>> > print-debugging macro the only use case I imagine of otherwise wanting
>> > something to be immediately accessible without package prefixing yet
>> > without modifying the package definition form.
>> >
>> > It's still time to remove that macro before the next release, but I
>> > believe it's the right thing to include it, and maybe some of you will
>> > agree with me and start using it, if not from the yet unrelease ASDF
>> > 3.1.1, perhaps from a copy in your .sbclrc.
>> >
>> > —♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org
>> > The common argument that crime is caused by poverty
>> > is a kind of slander on the poor.
>> >        — H. L. Mencken
>> >
> 
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