I'm programming and want to create a variable only if it does not already exist.

Is there a way to express this with a single word?

For example, if the variable already exists, I have the options

  • overwrite to overwrite the current value with a new value
  • append to append new data to existing data

I'm searching for the word to express if the data already exists, leave it alone, otherwise take the given data.

  • 1
    In database terms this is called an 'insert or update' – Mitch Oct 8 '15 at 15:05
  • This is a common scenario, but to my knowledge there is no single term that covers most of the possible situations. The closest, perhaps, is "singleton", but it only applies to a narrow range of problems (and, as a programming concept, it stinks). – Hot Licks Oct 9 '15 at 11:12

Merge is what you are looking for, at least in the SQL lexicon.

It is also called an Upsert, which indicates data can be updated where it exists and inserted where it does not.

This does not necessarily mean that existing data will be updated; existing data can be left as is.

Boring technical link

  • @eckes My initial answer was incomplete. Edited. – Eric Hauenstein Oct 8 '15 at 16:00

perhaps you want to ensure existence of the variable?

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