CommonQt enums and operators

Eric Eaton

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Oct 5, 2012, 10:31:14 PM10/5/12

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Hi, I'm a fairly new lisp user and I wish to create a graphical application. CommonQt seems decent but is there really only one page of documentation? In particular I am struggling to figure out how to use enums, they are not a numeric type and I can't find a way to convert them to numbers. Also Qt defines some useful overloaded operators which I can't access.

CL-USER> (defparameter *size* (#_new QSize 4 4))
*SIZE*
CL-USER> (#_operator+= *size* (#_new QSize 3 3))

; in: QT-INTERNAL::|operator14| +=
; (QT::FULL-RESOLVE-THIS +=)
;
; caught WARNING:
; undefined variable: +=
;
; compilation unit finished
; Undefined variable:
; +=
; caught 1 WARNING condition
;
; caught WARNING:
; undefined variable: +=
;
; compilation unit finished
; Undefined variable:
; +=
; caught 1 WARNING condition
; Evaluation aborted on #<UNBOUND-VARIABLE += {10030102E3}>.
CL-USER>

Anyone know if there is a way to accomplish these things?

budden

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Oct 9, 2012, 12:21:02 AM10/9/12

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Hi! I know nothing about CommonQt, but, some general hints: o know what is *STAR* try (describe '*star*), (describe *star*), use inspector of your lisp IDE etc; Qt reader (#_) _should_ be case sensitive while CL reader is not. Also, it _might_ treat "*" in special way. It is likely to misinterpret *star*, try *STAR* or, better, just give another name to your var:
(defparameter |Star| ...)

(#_operator+= Star (#_new QSize 3 3))

Eric Eaton

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Oct 10, 2012, 2:01:02 AM10/10/12

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Thanks for your reply.

The reader macro is for executing foreign functions. I am reasonably sure that it only reads the word following it, which is the name of the C++ method to be called. Overloading += in C++ is done by overloading the function named operator+=. So I assumed it would be the same in commonqt.

It appears that there is a function #_operator, and the += is being evaluated normally as the first argument and of course it is unbound. I have to figure out how to use it. There is no documentation which I can find on #_operator.

Eric Eaton

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Oct 10, 2012, 2:08:24 AM10/10/12

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...and that is because I probably created it when I used the macro.

Eric Eaton

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Oct 10, 2012, 2:29:18 AM10/10/12

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I did it! By making some trivial modifications to CommonQt. I feel like I've achieved some kind of hacker cred now XD don't spoil this for me. However I have become somewhat disenfranchised with common lisp and commonqt and I'm considering using clojure instead.

Raymond Wiker

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Oct 10, 2012, 12:36:54 PM10/10/12

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I'm reasonably sure that the reader macro is #_, and the argument is
"operator+=". That is, the reader macro does an FLI lookup of the symbol
named "operator+=", and applies it to the two arguments.

budden

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Oct 11, 2012, 4:58:10 AM10/11/12

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Hi! In case of "new" #_ also reads QSize so that it can tell it from QSIZE. This is what confused me, sorry for that.

Eric Eaton

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Oct 12, 2012, 2:33:59 AM10/12/12

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On Wednesday, October 10, 2012 9:36:54 AM UTC-7, Raymond Wiker wrote:

Yes that seems to be its function, but it was stopping before taking the + character from the stream and normal evaluation resumed on +=. The reader macro processed "operator" and interned a corresponding symbol as a side effect. I assumed this meant that the function actually existed. Changing the reader to accept the character + made everything better.