How much work should the constructor for an HTML parsing class do?

Question

How much work is it reasonable for an object constructor to do? Should it simply initialize fields and not actually perform any operations on data, or is it okay to have it

Answer 1

In my case, the entire contents of the HTML file are passed through a String. The string is no longer required once it is parsed and is fairly large (a few hundred kilobytes). So it would be best to not keep it in memory. The object shouldn't be used for other cases. It was designed to parse a certain page. Parsing something else should prompt the creation of a different object to parse that.

It sounds very much as though your object isn't really a parser. Does it just wrap a call to a parser and presents the results in a (presumably) more usable fashion? Because of this, you need to call the parser in the constructor as your object would be in a non-useful state otherwise.

I'm not sure how the "object-oriented" part helps here. If there's only one object and it can only process one specific page then it's not clear why it needs to be an object. You could do this just as easily in procedural (i.e. non-OO) code.

For languages that only have objects (e.g. Java) you could just create a static method in a class that had no accessible constructor and then invoke the parser and return all of the parsed values in a Map or similar collection