Analysis of information sources in references of the Wikipedia article "Rexx" in English language version.
A variety of internal and external calling mechanisms are defined. The most primitive is the command (which is quite similar to a message in the Smalltalk-80 system and in other object-oriented systems), in which a clause that consists of just an expression is evaluated. The resulting string of characters is passed to the currently selected external environment, which might be an operating system, an editor, or any other functional object. This ability to send commands to different environments is a primary concept of the language and is especially important when REXX is used as a "macro" language for extending applications.
Could there be a high astonishment factor associated with the new feature? If a feature is accidentally misapplied by the user and causes what appears to him to be an unpredictable result, that feature has a high astonishment factor and is therefore undesirable. If a necessary feature has a high astonishment factor, it may be necessary to redesign the feature.
A variety of internal and external calling mechanisms are defined. The most primitive is the command (which is quite similar to a message in the Smalltalk-80 system and in other object-oriented systems), in which a clause that consists of just an expression is evaluated. The resulting string of characters is passed to the currently selected external environment, which might be an operating system, an editor, or any other functional object. This ability to send commands to different environments is a primary concept of the language and is especially important when REXX is used as a "macro" language for extending applications.
Could there be a high astonishment factor associated with the new feature? If a feature is accidentally misapplied by the user and causes what appears to him to be an unpredictable result, that feature has a high astonishment factor and is therefore undesirable. If a necessary feature has a high astonishment factor, it may be necessary to redesign the feature.