{"id":7470,"date":"2024-09-13T10:11:42","date_gmt":"2024-09-13T08:11:42","guid":{"rendered":"https:\/\/oopm.org\/?page_id=7470"},"modified":"2024-11-18T09:07:46","modified_gmt":"2024-11-18T08:07:46","slug":"9-2-conditional-statements","status":"publish","type":"page","link":"https:\/\/oopm.org\/?page_id=7470","title":{"rendered":"9.2 Conditional statements"},"content":{"rendered":"
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A conditional statement is a statement that execute different statements depending on the value of a boolean expression.<\/p>\n\n\n\n

If:then<\/h2>\n\n\n\n

The if:then<\/code> statement used in previous sections is an example of a conditional statement. The code below shows a sketch of a definition of if:then<\/code> as a control method.<\/p>\n\n\n\n

if(cond: var<\/strong> boolean):then{thenPart:< Object}:\n   ...<\/code><\/pre>\n\n\n\n
As mentioned, if:then<\/code> is a built-in primitive control method in qBeta and cannot be defined in terms of other language mechanism.<\/p>\n\n\n\n
Defining if:then:else<\/h2>\n\n\n\n
The if:then:else<\/code> is an example of a control method that may be define as method in qBeta. You may find the following definition in the qBeta library:<\/p>\n\n\n\n
if(cond: var<\/strong> boolean):then{thenPart:< Object}\n                     :else{elsePart:< Object}:\n   if (cond) :then  \n      thenPart\n      leave(if:then:else)\n   elsePart<\/code><\/pre>\n\n\n\n
The control <\/mark>method has the following structure:<\/p>\n\n\n\n
    \n
  • The name of the control method is if:then:else<\/code>.<\/li>\n\n\n\n
  • It has three parameters, cond<\/code>, which is a boolean<\/code>, thenPart, which is a virtual Object<\/code>, and elsePart<\/code>, which also is a virtual Object<\/code>.<\/li>\n\n\n\n
  • The parameters are specified using the fat-comma syntax as described in section