getstring prompt

[dvertz]

Is there a way to use getstring and have a default that will also accept a null string?

For example, if issued the normal way as:

(setq pre (getstring "\nPrefix <C->: "))

Then the normal way is check if the variable pre is null and if it is then set the variable pre to "C-1"

But what I am wanting to do is issue the prompt as:

(setq pre (getstring "\nPrefix: C- "))

Then if the C- is removed the variable pre would be a null string, but if not removed then the variable is filled with "C-"

Is there a way to do that?

Thanks

[ВeekeeCZ]

getkword with arbitrary input could help. 

(progn (initget 128) (getkword "\nPrefix <C->: "))

[dvertz]

Good Thought, but not quite there. When I enter that and just press enter, NIL is returned. I could process NIL and set the variable to "C-" but the result is the same as with getstring. So I thought maybe if I included "C-" in the initget like (initget 128 "C-") that it might return "C-", but it does not. I am thinking that what I want may not be able to be done. As the only thing I can think of would be to have the getstring issue the prompt and then a princ to add the "C-" as an answer. That way the "C-" could be deleted and a NULL string could be returned, but if the "C-" is left as the answer to getstring then the "c-" would be returned. However, a princ would not place the "C-" as answer to getstring until getstring IS answered.

[ВeekeeCZ]

Lost, sorry.

One more tip, though,

(lisped "C-")

[DGCSCAD]

If I'm following you correctly, maybe something like this:

(initget "Yes No")

(setq pre (getstring "\nDo you want a Prefix of C- ? [Yes/No] <Y>"))

(if (or (= pre "") (= pre "Y"))

   (setq pre "C-")

   (setq pre nil)

)

[dvertz · Accepted solution]

Perfect, you got me there.

I used:

(initget "Yes No")
(setq pre (getstring "\nDo you want a Prefix of \"C-\"? [Yes]"))
(if (= pre "Y") (setq pre "C-"))

The results were:

Command: (setq pre (getstring "\nDo you want a Prefix of \"C-\"? [Yes]"))
Do you want a Prefix of "C-"? [Yes]V- (the "V-" was entered)
"V-"
Command: (setq pre (getstring "\nDo you want a Prefix of \"C-\"? [Yes]"))
Do you want a Prefix of "C-"? [Yes] (nothing was enter and just pressed enter)
""
Command: (setq pre (getstring "\nDo you want a Prefix of \"C-\"? [Yes]"))
Do you want a Prefix of "C-"? [Yes]Y (clicked the Yes)
"Y"

This worked perfectly, I am able to process all three answers.

I am curious why only the "Y" was returned instead of the whole word "Yes".

[-didier-]

Bonjour @dvertz 

oops! When editing my post, some answers were posted. I’m not fast enough!

I am not sure to understand correctly your question.

I propose that if press “return” at the prompt without giving an answer, you concatenate the prefix and the number 1.

 Amicalement

[DGCSCAD]

Apparently, the INITGET isn't required, and I've also found something I didn't know when looking into this:

Using GETSTRING where GETKWORD would normally be used, if you supply brackets the first capitalized letter within the brackets is used as a selectable character and will return that as a string if selected.

Command: (setq pre (getstring "\nDo you want a Prefix of \"C-\"? [ZeRo]"))
Do you want a Prefix of "C-"? [ZeRo]Z
"Z"

Command: (setq pre (getstring "\nDo you want a Prefix of \"C-\"? [zeRo]"))
Do you want a Prefix of "C-"? [zeRo]R
"R"

[doni49]

---

@dvertz wrote:

I am curious why only the "Y" was returned instead of the whole word "Yes".

---

It uses the CAPITALIZED letters from the initget function.  Try this version and it'll return YES -- but you'll have to actually type YES (you don't have to type it in caps though).

(initget "YES NO")
(setq pre (getstring "\nDo you want a Prefix of C- ? [Yes/No] <Y>"))

[Kent1Cooper]

---

@dvertz wrote:

....

(setq pre (getstring "\nPrefix <C->: "))

Then the normal way is check if the variable pre is null ....

....

I am curious why only the "Y" was returned instead of the whole word "Yes".

---

Bear in mind that unlike other (get...) functions, (getstring) does not return nil if you press Enter, but rather an empty text string "".  [I'm never quite sure when people use the word "null" whether they mean "nil."]

....

You would need to do the (initget) again before each (get...) function -- once at the top will not cover more than one of them.

[dvertz]

Well, after all these years, I learned something new here.

The getstring returns only the "Y"

But the getkword returns the entire work "Yes" as it appears in the initget function

[Kent1Cooper]

I wouldn't bother with the Yes/No choice.  Does this do what you want?

(setq pre (getstring "\nPrefix <C->: "))

(if (= pre "") (setq pre "C-"))

[dvertz]

Thanks.

The null string is exactly what I wanted to have return when nothing is entered. I could have also used having it return NIL. With NIL I could assign the NULL string. The key was having the option of the default value of "C-". But yet also have an option of typing in a different value for example "V-". Just as DGCSCAD got me to.

[dvertz]

Kent,

As pointed out in post 1, it does not.

As pointed out in post 6 with the help of the forum, I got there.

Thanks though. I always appreciate all who help.

[komondormrex]

one using cond

(setq pre (cond ((= "" (setq pre (getstring "\nEnter prefix {C}-: "))) "C-") (t (strcat pre "-"))))

[ВeekeeCZ]

Here's the getkword version

(defun c:test ()
  (initget 128)
  (setq o (cond ((getkword "\nPrefix <C->: ")) ("C-")))
  (setq o (vl-string-trim "\"" o))
  (princ (strcat "Prefix: " o))
  (princ)
  )

Simple <enter> to get "C-"

"" (double quotes) to get an empty string ""

"C :"  - quotes have to be typed to set anything with a space.