问题
I am trying to write a method which returns a new value. Following code is modified from here:
| stripChars |
stripChars := [ :string :chars |
str := string reject: [ :c | chars includes: c ].
str displayNl. "THIS WORKS."
^ str "THIS DOES NOT WORK."
].
newstr := stripChars
value: 'She was a soul stripper. She took my heart!'
value: 'aei'.
newstr displayNl.
Although above function creates new string and displays it, there is error in returning or receiving returned new string:
$ gst make_fn_ques.st
Sh ws soul strppr. Sh took my hrt!
Object: 'Sh ws soul strppr. Sh took my hrt!' error: return from a dead method context
SystemExceptions.BadReturn(Exception)>>signal (ExcHandling.st:254)
SystemExceptions.BadReturn class(Exception class)>>signal (ExcHandling.st:151)
String(Object)>>badReturnError (Object.st:1389)
UndefinedObject>>executeStatements (make_fn_ques.st:10)
nil
Where is the problem and how can this be solved? Thanks for your help.
回答1:
The
^ str
does not return from the block (stripChars), but from the enclosing method instead (non-local return).
Apparently GNU Smalltalk does not allow you to return from the script that you pass to gst in this way.
Just drop the ^, and keep only str
as the last expression of the block. That will cause str
to be the return value of the block.
来源:https://stackoverflow.com/questions/56100101/why-this-methods-return-part-is-not-working