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Abstract type: Difference between revisions
→{{header|Simula}}
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EQUALTO := T = K QUA TEXTHASHKEY.T;
END TEXTHASHKEY;
</lang>
=={{header|Smalltalk}}==
A class is declared abtract by responding to the query <tt>isAbstract</tt> with true, and defining the required protocol for subclasses to raise an error notification. Optionally, instance creation can be blocked. Typically, the IDE provides a menu function to generate these definitions automatically:
<lang smalltalk>someClass class >> isAbstract
^ true
someClass class >> new
^ self abstractClassInstantiationError
someClass >> method1
^ self subclassResponsibility
</lang>
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