How's my code??

jonathann3891 · 发表于 2022-7-5 19:58:18

I wrote a lisp to draw a pipe break.

Is it coded efficent?

I'd like to have it check if the layer is frozen, if it is thaw it. (same with if its off)

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(defun c:pb (/ olayer)(setq olayer (vlax-variant-value (vla-getvariable (vla-get-activedocument                        ;remembers current layer(vlax-get-acad-object)) "clayer")))(setq pt1 (getpoint "\n Select First Point: "))(setq pt2 (getpoint "\n Select Second Point: ") dist (distance pt1 pt2) ang (angle pt1 pt2) pt3 (polar pt1 ang (/ dist 2.0)));end setq(if (not (tblsearch "layer" "c_gen_Dimn"))                                                        ;check to see if layer exist if not create it(command "_.layer" "m" "c_gen_Dimn" "c" "132" "" "")                                                 ;create layer(setvar "clayer" "c_gen_Dimn")                                                                        ;set layer new layer current current)(setvar "plinewid" 0.0)(command ".pline" pt2 "arc" "angle" "80" pt3 pt1 "angle" "-80" pt3 "")(vla-setvariable (vla-get-activedocument (vlax-get-acad-object)) "clayer" olayer)                ;return to previous layer(princ))

Commandobill · 发表于 2022-7-5 20:11:29

From what I see there is nothing wrong with your code. Programming is an art. With codes like you have, there really isn't a wrong way to do it if it works. People like Lee-Mac will write a code 3 different ways just because it's possible. There are a few things you can do differently, but what you have seems to be fine.

Commandobill · 发表于 2022-7-5 20:12:17

For instance, you could have gotten your midpoint using this:

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(defun mid (p1 p2) (list   (/ (+ (car p1) (car p2)) 2.0)   (/ (+ (cadr p1) (cadr p2)) 2.0) ))

But your way also works. You could also Get and Set your layers variables thus:

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(setq olayer (getvar 'clayer))(setvar 'clayer olayer)

Which you use at some points in your code. But again, using vla is not a bad option. Lastly, some people find that using "command line cop-outs" is less efficient. So if you wanted to create your layer or polyline using another method, you could.

jonathann3891 · 发表于 2022-7-5 20:20:35

I'm a newb when it comes to coding, but I desperately want to learn.

I searched and found the vla for remembering layers and applied it to my code. I didnt write it myself

I like the setvar options better, I understand it better. The vlax seems to go through alot of steps just to remember 'clayer.

Commandobill · 发表于 2022-7-5 20:30:19

Everyone starts somewhere. Most of the time when you are trying to write code you find pieces of it already written, and you can just apply it to your code.

David Bethel · 发表于 2022-7-5 20:32:39

A robust SteLayer call needs to include a god bit off error trapping

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;++++++++++++ Make Layer Current +++++++++++++++++++++++++++++++++(defun SetLayer (name / ldef flag) (cond ((or (not name)    (not (snvalid name)))(princ "\nBad Aurgment Passed To SetLayer - ")(prin1 name)(exit))) (command "_.LAYER") (if (not (tblsearch "LAYER" name))     (command "_Make" name)     (progn      (setq ldef (tblsearch "LAYER" name)     flag (cdr (assoc 70 ldef)))      (and (= (logand flag  1)  1)    (command "_Thaw" name))      (and (minusp (cdr (assoc 62 ldef)))    (command "_On" name))      (and (= (logand flag  4)  4)    (command "_Unlock" name))      (and (= (logand flag 16) 16)    (princ "\nCannot Set To XRef Dependent Layer")    (quit))      (command "_Set" name))) (command "") name)

The (exit) call is totally up to you and your style of coding.

-David

neophoible · 发表于 2022-7-5 20:42:14

I agree that you have to start somewhere.  If you want to learn, I've no  doubt you will.  Going through the alternate versions here should help,  though some will be harder to understand than others.  I'm sure if you ask, someone will explain the reasoning behind the code.

I applaud your use of comments in your routine.  That can be very important when you want to edit it later, but have long forgotten what you were thinking at the time you were writing the program.

One thing I would  point out here is that it is generally good practice to keep your variables local  to a routine, which is what the slash mark is for on your top line.  This way you don't have to worry about their values being overwritten anywhere, or overwriting any globals from another routine.  To make them local you would simply include all the other variable names after clayer.  Something like this:

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(defun c:pb (/ olayer pt1 pt2 pt3 dist ang)

However, this does mean that you cannot easily check their values in the drawing session after the routine has run.

Happy LISPing!

BIGAL · 发表于 2022-7-5 20:49:35

I aggee with getvar shorter than VL, I would suggest that you consider a library style of common functions like "does layer exist" by making it a defun like David's and auto load it, it is very useful that all your code can have a quick check layer which only needs 1 line (setlayer layname)

Commandobill · 发表于 2022-7-5 20:57:46

I totally agree with BIGAL. If you do have a sub function (like the mid function I posted earlier) it is generally good practice to put it inside your main function. Hopefully I don't lose you here, but... If you have a sub function inside your main function it acts as a "private function" ie you can't call it from a completely separate program. if you have it in your routine outside your main program it will act as a global function, which can be called form any other function. If you decide to alter the function on a program to fit your needs, it may not work on other functions that you call it.

Hope that's not confusing.

BIGAL · 发表于 2022-7-5 21:01:38

Just following on the library lisp can be any name and there are various ways to autoload it, one of mine has 82 defuns in it. In a particular suite there are 8 defuns used every time in the majority of the lisps, these all being in the "Library". There are so many good defuns out there I would start with some common ones like the entmakes LINE PLINE CIRC ARC, it also means your code is consistent in the methods used. Make sure you add good comments about what they do and leave original authors etc.

I am about to rewrite all my plot routines 12 off, into one and have a dcl front end so it will have common used defuns.

[编程交流] How's my code??

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