Re: How to test if a variable is declared?

[David]

On Fri, 13 Mar 2020 at 13:59, Peng Yu <address@hidden> wrote:

> What is the best way
> to test whether a viable is declared?

[answers were given and rejected because ...]

On Fri, 13 Mar 2020 at 23:56, Peng Yu <address@hidden> wrote:
>
> it will use extra CPU for a test that could be made more light weight.

On Sat, 14 Mar 2020 at 01:01, Peng Yu <address@hidden> wrote:
>
> it could be supported for example by adding a new switch to [[.

But adding a new switch to [[ will use extra CPU every time [[ is called.

Why should everyone's code run slower just because you had a hypothetical dream?