Escape HTML tags in Smalltalk String

Question

I'm desperately trying to write a very basic method in Smalltalk to escape HTML tags ('<' and '>').

So far, this is what I have come up with:

escapeHtml: str
    |tags newString tmpString|
    newString := String new.
    tags := Dictionary new.
    tags at: '<' put: '&lt;'.
    tags at: '>' put: '&gt;'.
    tags keysAndValuesDo:
    [ :k :v |
        tmpString := str copyReplaceAll: k with: v.
        newString := tmpString
    ].
    ^newString
!

Unfortunately, it appears to only replace the very last item of the tags dictionary. What am I doing wrong? I should probably also point out that I have very little experience with Smalltalk.

The Interpreter of choice is 'syx'.

Answer 1

I think that you wanted to make something like

newString := str

and then in keysAndValuesDo: block:

tmpString := newString copyReplaceAll: k with: v.

because right now you are generating a tmpString for each key/value pair with only one key replaced. Than you assign it to the newString. To achieve your goal you should send copyReplaceAll: to the string that was processed on previous iteration. This can be done by sending a message to a newString, but for first iteration to work you should assign a value of an str to it.

P.S. I also think that this cleaner version should work:

escapeHtml: str
    |tags newString|
    newString := str copy.
    ...
    tags keysAndValuesDo: [ :k :v | newString replaceAll: k with: v ].
    ^newString