On Mon, 2007-05-07 at 16:26 +0200, Damien Cassou wrote:

Hi Norbert,

2007/5/7, Norbert Hartl norbert@hartl.name:

...

    error signal = true
            ifTrue:
                    [self reset.
                    self logout.
                    self reLogin.
                    exception restart]

This code comes from VW. Is the signal method implemented differently under VW. In squeak the "error signal" itself throws the error so there is no ifTrue: evaluation, right?

Are you sure that 'error' is an instance of Exception or one of its subclasses? Maybe it's something else.

No, it is

handleError: exception for: command | errorClass error | errorClass := command isReadCommand ifTrue: [GlorpDatabaseReadError] ifFalse: [GlorpDatabaseWriteError]. error := errorClass new. error command: command. error databaseError: (self innerExceptionFor: exception). error accessor: self. error signal = true ifTrue: [self reset. self logout. self reLogin. exception restart] ifFalse: [error return: nil].

And GlorpDatabaseReadError has Error as super super class.

Moreover, I don't see the point of 'something = true ifTrue:'. Why not: 'something ifTrue:'?

Me neither but I didn't write it ;) And it is no problem so far.

Norbert

2007/5/7, Norbert Hartl norbert@hartl.name:

On Mon, 2007-05-07 at 16:26 +0200, Damien Cassou wrote:

...

Hi Norbert,

2007/5/7, Norbert Hartl norbert@hartl.name:

...

    error signal = true
            ifTrue:
                    [self reset.
                    self logout.
                    self reLogin.
                    exception restart]

This code comes from VW. Is the signal method implemented differently under VW. In squeak the "error signal" itself throws the error so there is no ifTrue: evaluation, right?

I think I understand (I've just read the squeak unit tests :-)).

When 'error signal' is sent, the exception is raised. The method execution stops. Somewhere in the stack, the method should be captured like:

[self doSomethingThatMightRaiseAGlorpDatabaseReadError] on: GlorpDatabaseReadError do: [:exc | self manageTheException. exc resume: true]

or

resume: false

Then the control is sent back to where the exception has been raised. What was passed to #resume: is returned by #signal.

From: Damien Cassou

Hi Norbert,

2007/5/7, Norbert Hartl norbert@hartl.name:

Moreover, I don't see the point of 'something = true ifTrue:'. Why not: 'something ifTrue:'?

-- Damien Cassou

I didn't write the code but as a warning it's not always a good idea to remove this type of pattern. I have seen code like this when the result of something is not always a Boolean. Most of the time the results are true false or nil, but sometimes something returns an object or a Boolean. Most of the time it can be rewritten to return only a Boolean which would be the right solution but I've seen some pretty bad code that is better left then mucked with. (Again I haven't looked to see if this is the case with this Glorp code)

As you point out it is usually just bad coding but once bitten ...

Ron Teitelbaum