Otdfbt

It is a bit odd we can't evaluate a switch statement directly on SObjectType, so I am trying to determine conclusively which workaround is the most efficient.

Just to verify, I tried to compile this code:

void demo(SObjectType input)

 switch on input
 
 when Account.sObjectType 
 when else 
 

And this code generates the error:

Schema.SObjectType is not a valid switch expression type

Bummer. There are workarounds however. The two most obvious that I have come up with:

void demoRecordInstantiation(SObjectType input)

 switch on input.newSObject()
 
 when Account a 
 when else 
 

void demoStringTyping(SObjectType input)

 switch on String.valueOf(input)
 
 when 'Account' 
 when else 
 

Maybe there are others, so if there is an obvious approach I have missed which performs better or is more readable/maintainable, let me know.

My question is, what approach offers the best performance? If I am calling this method many times in a loop, is the SObjectType.newSObject method resource intensive? Or calling String.valueOf(SObjectType)? Should I consider caching these values?

The when values must be literals, so you cannot use String.valueOf as demonstrated in your second example. That said, using String.valueOf is approximately 10% more efficient when using literal string values:

Long t3, t2, t1 = datetime.now().gettime();
for(Integer i = 0; i < 100000; i++) 
 sobjecttype a = account.sobjecttype;
 switch on a.newsobject() 
 when account ac 

 
 when contact co 

 
 

t2 = datetime.now().gettime();
for(Integer i = 0; i < 100000; i++) 
 sobjecttype a = account.sobjecttype;
 switch on string.valueof(a) 
 when 'Account' 

 
 when 'Contact' 

 
 

t3 = datetime.now().gettime();
system.debug(t3-t2);
system.debug(t2-t1);

That said, it appears that the actual performance difference is insignificant (less than 0.008 ms per call), so unless you need the performance, choose whichever works best for you.

As an aside, make sure you comment this code for followup later. It has been said salesforce.com would like to include other data types in future releases, and this may include the sObjectType data type as well.