Protection of 4D Write Pro dynamic expression evaluation

With 4D v16, 4D Write Pro is now providing a higher level of protection regarding the evaluation of 4D expressions in documents.
Developers can now fully rely on 4D for checking the evaluation of these expressions. By doing so, end-user machines and databases will be automatically protected from any possible side effects.

A valid 4D expression can be a field, a variable, a 4D command, a statement returning a value, a project method, and so on.

Starting with 4D v16, “unsafe” 4D expressions will no longer be evaluated and an error will be displayed instead.

To be considered safe, an expression must contain:
• only allowed 4D commands (same list as Formula Editor)
• only allowed 4D Methods (declared by the 4D Developer using the SET ALLOWED METHODS command)

This security mechanism can be disabled through “Database Settings” in the “Data Access” section of the “Security” tab:

To know more about this feature, you can take a look at the following “How Do I” database:

Database Example

For more details, please take refer to the related article in 4D v16 documentation.