Check existence of variable

[Ian Krukow]

Hi all,

is there any way in Asymptote to check whether a variable exists? Maybe via error handling (like try-except in python)? An alternative would be to search the fields of a structure and check whether a field name exists, but I have not found anything on that either.

Can anyone help me?
Kind regards
Ian

[Charles Staats]

To the best of my knowledge, there is no way to check dynamically whether a variable exists. The closest thing I can think of that works is to check whether a struct or array is null. Example:

struct foo {
  real x;
}
// Initialize to null [NOTE: "=null" is required here.]
foo myreal = null;

// \vdots

if (alias(myreal, null)) {
  myreal = new foo;
  myreal.x = 17;
}

I would also note that Asymptote does not support error/exception catching.

What is your use case?