Code as Data | Request for EVAL() function

[Joseph_Seddik]

Dear AppSheet team,

This is a simple incremental change request, that should put AppSheet into another level in terms of functionality and usability. AppSheet's main mission, as I see it, is developing data-driven applications, therefore, improvements in data processing capabilities should go in line with AppSheet's strategy. 

My request is to enable app creators to dynamically write column expressions during the app's runtime. This will turn AppSheet into a powerful Machine Learning, Testing and Quality Control platform. Additionally, given this capability, the creativity of AppSheet's developers will extend AppSheet to a plethora of use cases. 

This can be easily done by adding an EVAL() function, that would take a text input, evaluate it as an AppSheet expression in the relevant context, and return the return value of the input expression. 

EVAL() function would typically be used in an App Formula of a column, as well in column constraints. 

The input expression would be for example stored in a dedicated LongText column that would be dynamically updated by the app, in an iterative learning process conceived by the app developer, considering the result of the EVAL() expression. 

Syntax

EVAL( expressionText )

Arguments

expressionText (LongText)

Return Value

The return value of the evaluated expression.
The app creator should correctly set the type of the column where EVAL() is used according to the expected return value of the evaluated expression.

Examples:

• EVAL([column])
• EVAL([ref].[column])

[Meyverick]

Example: 

[formula] = "x * 10"
[value] = 1
EVAL(DECIMAL(SUBSTITUTE([formula], "x", [value]))) = 1 * 10 = 10