November 2012
Intermediate to advanced
888 pages
54h 46m
Polish
Content preview from Ruby. Receptury
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18.3. Wymaganie określonej wersji gemu
Problem
Nasz program zależy od interfejsu bądź pewnej własności gemu dostępnej tylko w określonych wersjach biblioteki. Jeśli użytkownik spróbuje uruchomić program z zainstalowaną nieprawidłową wersją gemu, powinna wyświetlić się informacja o wymaganej wersji, tak by użytkownik mógł dokonać aktualizacji.
Rozwiązanie
W bibliotece rubygems zdefiniowano metodę — Kernel#require_gem, która pozwala na definiowanie warunków dotyczących gemów. Metoda zgłosi wyjątek Gem::LoadError, jeśli określonego gemu nie zainstalowano lub jeśli żadna z zainstalowanych wersji gemu nie spełnia postawionych wymagań.
Najłatwiejszym rozwiązaniem jest zezwolenie na instalację dowolnej wersji gemu. W takim przypadku wcale ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.