将SAS语句分配给宏变量

Question

我有一个数据集，其中包含我想为宏中的数据集定义的变量的名称和属性。例如：

variable_name = "filedate"  
variable_length = 8  
variable_label = "Date file was loaded"  
variable_format = "date9."
variable_derivation = "filedate = today()"

宏做的是这样的：

%macro create_ds;  

    data _null_;
    set variable_definitions;
        call symputx('varname', variable_name);
        call symputx('varlength', variable_length);
        call symputx('varlabel', variable_label);
        call symputx('varformat', variable_format);
        call symputx('varderive', variable_definition);
    run;  

    data newds;
        attrib &varname length=&varlength label="&varlabel" format=&varformat;
        &varderive;
    run;

%mend create_ds;

我希望datastep看起来像是：

data newds;
    attrib filedate length=8 label="Date file was loaded" format=date9.;
    filedate = today();
run;

我实际得到的是：

data newds;
    attrib filedate length=8 label="Date file was loaded" format=date9.;
    .;
run;

然后抛出错误，因为“。”不是有效的陈述。

有没有办法将一个datastep语句分配给一个宏变量并实际让它执行？