Running an extended command with default input?

Running an extended command with default input?

[egarrulo]

How can you run an extended command with a default input?  For example: 
`eval-expression` with `(+ 1 1)` as default input (in other words: what 
you would accomplish by typing `M-: (+ 1 1)` without RET).  This code 
works, but it seems to add an implicit RET:

(execute-kbd-macro (vconcat (kbd (substitute-command-keys 
"\\[eval-expression] "))
                             "(+ 1 1)"))

Thanks.

Re: Running an extended command with default input?

[John Mastro]

egarrulo <egarrulo@gmail.com> wrote:
> How can you run an extended command with a default input? For example:
> `eval-expression` with `(+ 1 1)` as default input (in other words:
> what you would accomplish by typing `M-: (+ 1 1)` without RET). This
> code works, but it seems to add an implicit RET:
>
> (execute-kbd-macro (vconcat (kbd (substitute-command-keys "\\[eval-expression] "))
>                             "(+ 1 1)"))

One option is to define your own command, which reads the input itself
(providing the default) and then invokes the underlying command. For
instance, for ‘eval-expression’ you could do something like:

    (defun my-eval-expression (exp &optional insert-value)
      (interactive (list (read--expression "Eval: " "(+ 1 1)")
                         current-prefix-arg))
      (eval-expression exp insert-value))

-- 
john