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Context:

A common access check or modifier is to use something like: require(boolMapping[msg.sender] == true); to ensure the caller is approved to use a function.

Since mapping (address => uint256) uintMapping defaults all unset values to 0, my question is:

Question: Is it safe to use this:

require(uintMapping[msg.sender] > 0, "not authorised");

instead of this:

require(boolMapping[msg.sender] == true, "not authorised");

to restrict use of a function, assuming pre-authorised accounts are set with values greater than zero?

(This would help condense the amount of storage required on a contract where users already have associated non-zero numbers, as we wouldn't need to use a struct or a second auth mapping).

Thank you!

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    Why? If zero isn't a valid value then it should be fine, but you have to enforce when saving to the mapping that zero isn't stored.
    – Ismael ♦
    Commented Jan 29, 2022 at 19:54
  • Thanks @Ismael . Good point about enforcing non-zero values for members in the mapping. The reason is to save a bit of gas and increase efficiency with my storage structures (previously I had a uintMapping and a boolMapping, but the boolMapping was only ever used to check authorisation before using the uintMapping).
    – panda
    Commented Jan 29, 2022 at 20:50

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As far as I know, there shouldn't be any issue with this approach.

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