Setting a page number from the URL, with fallbacks

You could re-write it something like this:

<cfif StructKeyExists(stElement,'idInfoPage') AND isNumeric(stElement.idInfopage)>
    <cfset idInfopage = stElement.idInfopage />

<cfelseif StructKeyExists(Url,'idInfoPage') AND isNumeric(Url.idInfopage)>
    <cfset idInfopage = Url.idInfopage />

<cfelse>
    <cfset idInfopage = 0 />

</cfif>

Notes on the changes:

• StructKeyExists is generally recommended over isDefined.
• isNumeric wont return true for empty string.

If you have a lot of code like this, it might make sense to create a function, something like:

<cfset idInfopage = getNumberOrZero('idInfopage',stElement,Url) />

Then implemented as:

<cffunction name="getNumberOrZero" returntype="numeric" output=false
    hint="Loops through structs (args 2..n) looking for number; else return 0">
    <cfargument name="Key" type="String" required />
    <cfset var i = 0 />

    <cfloop index="i" from=2 to=#ArrayLen(Arguments)#>
        <cfif StructKeyExists(Arguments[i],Arguments.Key)
            AND isNumeric(Arguments[i][Arguments.Key])
            >
            <cfreturn Arguments[i][Arguments.Key] />
        </cfif>
    </cfloop>

    <cfreturn 0 />
</cffunction>