Assign only if not already defined in Julia

Question

Is there simple Julia syntax for assigning to a variable only if it is undefined (or falsy)? I mean something like Ruby's `x ||= NEW_VALUE`. I have tried `x || x=NEW_VALUE` but it throws an error. Barring easy syntax, what function can I use to check if a variable is defined?

Accepted Answer

You can use the `@isdefined` macro: `(@isdefined x) || (x = NEW_VALUE)`.

Assign only if not already defined in Julia

Solution

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