*允许未解析变量*在Clojure中做什么？

就像没有官方文件一样 允许未解决的VAR道歉-这不是一个完整的答案。我还没有弄清楚这件事的一切

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*允许未解析的变量*

定义在：

并用于：

显然，它在这里的用途是决定当遇到未解析的符号时，是否应立即抛出异常

你可以这样处理它：

myns.core=> (ns clojure.core)
nil

clojure.core=> oops!
CompilerException java.lang.RuntimeException: Unable to resolve symbol: oops! in this context, compiling:(/tmp/form-init1596111142512149454.clj:1:884) 

clojure.core=> (defn q [] (oops!))
CompilerException java.lang.RuntimeException: Unable to resolve symbol: oops! in this context, compiling:(/tmp/form-init1596111142512149454.clj:1:12) 

clojure.core=> (def *allow-unresolved-vars* true)
Warning: *allow-unresolved-vars* not declared dynamic and thus is not dynamically rebindable, but its name suggests otherwise. Please either indicate ^:dynamic *allow-unresolved-vars* or change the name. (/tmp/form-init1596111142512149454.clj:1)
#'clojure.core/*allow-unresolved-vars*

clojure.core=> oops!
IllegalArgumentException UnresolvedVarExpr cannot be evalled  clojure.lang.Compiler$UnresolvedVarExpr.eval (Compiler.java:1771)
clojure.core=> 

clojure.core=> (defn q [] (oops!))
CompilerException java.lang.VerifyError: (class: clojure/core$q, method: invoke signature: ()Ljava/lang/Object;) Unable to pop operand off an empty stack, compiling:(form-init1596111142512149454.clj:1:1) 

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但我还没有弄清楚它的用途，因为未解析的变量仍然会导致错误——它们只是不同的错误。另外，我不理解重新定义时的警告，因为警告说它不是声明为动态的，而在我看来，它在RT.java中似乎是声明为动态的。

似乎只在内部使用，一个省略未解析符号的标志，使编译成为不可操作的。您得到警告是因为您正在重新定义它，而不是设置现有的。您可以使用

altervar root

或者

set，根据上下文修改现有变量。
    if(o == null)
        {
        if(RT.booleanCast(RT.ALLOW_UNRESOLVED_VARS.deref()))
            {
            return sym;
            }
        else
            {
            throw Util.runtimeException("Unable to resolve symbol: " + sym + " in this context");
            }
        }

myns.core=> (ns clojure.core)
nil

clojure.core=> oops!
CompilerException java.lang.RuntimeException: Unable to resolve symbol: oops! in this context, compiling:(/tmp/form-init1596111142512149454.clj:1:884) 

clojure.core=> (defn q [] (oops!))
CompilerException java.lang.RuntimeException: Unable to resolve symbol: oops! in this context, compiling:(/tmp/form-init1596111142512149454.clj:1:12) 

clojure.core=> (def *allow-unresolved-vars* true)
Warning: *allow-unresolved-vars* not declared dynamic and thus is not dynamically rebindable, but its name suggests otherwise. Please either indicate ^:dynamic *allow-unresolved-vars* or change the name. (/tmp/form-init1596111142512149454.clj:1)
#'clojure.core/*allow-unresolved-vars*

clojure.core=> oops!
IllegalArgumentException UnresolvedVarExpr cannot be evalled  clojure.lang.Compiler$UnresolvedVarExpr.eval (Compiler.java:1771)
clojure.core=> 

clojure.core=> (defn q [] (oops!))
CompilerException java.lang.VerifyError: (class: clojure/core$q, method: invoke signature: ()Ljava/lang/Object;) Unable to pop operand off an empty stack, compiling:(form-init1596111142512149454.clj:1:1)