Am 16.07.2014 um 11:12 schrieb Max Bareis <i...@derverkoster.de>: > The misunderstanding her is based in the error message of the ui. > when you write > ^ - self width. > and save, the UI writes this text into the code: > ^ only numbers may be negated ->- self width. > > More helpful would have been something like: „only literals may be negated > with - use <object> negated instead“.
Then it needs to be "only number literals…" > > I was irritated and on the wrong track because I was absolutely sure that > self width is a number. > There is a difference between an object and the way you can instantiate it. The minus sign relates to the fact that smalltalk has syntax for numbers and the minus sign is part of that syntax enabling you to instantiate negated numbers. As soon as the object is created you can only send messages. Norbert > Am 16.07.2014 um 10:44 schrieb Alain Busser <alain.bus...@gmail.com>: > >> That's where the Inspector comes in: >> >> To debug, it is good to insert a self width inspect so that the inspector >> opens up and reveals what exactly the width is. OK, it is a number; then >> open the browser and look at the number's methods; or in the finder, try 2 . >> -2 in the examples... >> >> Pharo is excellent at debugging, that is why I choosed it for my Ontology >> project, the browser shows welle what is a number, what kind of numbers >> there are, and why a complex number is not a number... >> >> Alain >> >> >> On Wed, Jul 16, 2014 at 2:59 AM, Verkoster Info <i...@derverkoster.de> wrote: >> It definitely is, >> >> >> >> >> thanks for all your answers… >> >> Regards >> >> Max >> >> Am 16.07.2014 um 00:56 schrieb Camille Teruel <camille.ter...@gmail.com>: >> >>> I've been overtaken :) >>> Isn't that an active mailing list ? >>> >>> >>> On 16 juil. 2014, at 00:53, Camille Teruel <camille.ter...@gmail.com> wrote: >>> >>>> Hi Max, >>>> >>>> Pharo doesn't have syntax for prefix operator like "-". >>>> The parser does accepts a "-" before literal numbers but it's not possible >>>> for arbitrary expressions. >>>> However you have the message #negated . >>>> >>>> negatedWidth >>>> ^ self width negated >>>> >>>> Cheers, >>>> Camille >>>> >>>> On 16 juil. 2014, at 00:16, Verkoster Info <i...@derverkoster.de> wrote: >>>> >>>>> Hi, >>>>> >>>>> I am using latest Pharo 3.0 + vm. >>>>> >>>>> I have a method width with >>>>> width >>>>> >>>>> ^ 115 * self ratio. >>>>> in my understanding it returns a Number. >>>>> >>>>> When I try to create a method >>>>> negatedWidth >>>>> >>>>> ^ - (self width). >>>>> >>>>> the UI tells me that only Numbers may be negated. I am not able to save >>>>> the method. Am I on a wrong path or should that work and if how can I >>>>> avoid the UI error message? >>>>> >>>>> Regards >>>>> >>>>> Max >>>>> >> >
