compiler-errors - 埃菲尔:or and and and 中的本地声明编译失败
问题描述
编译器抱怨未知标识符,似乎它无法识别我的多个声明中的任何一个,我错在哪里?
if attached {INTEGER_REF} field.item as l_int
or attached {INTEGER_64} field.item as l_int
or ( attached {TUPLE} field.item as l_tuple and then attached {INTEGER_64} l_tuple.item (1) as l_int ) then
Result.put_integer (l_int.to_integer_64, primary_key_db_column_name)
elseif attached {STRING} field.item as l_s then
Result.put_string (l_s, primary_key_db_column_name)
end
更新
由于这似乎是一个有效的表达式,我认为如果在 my或a的每个分支中l_int
声明我应该能够在then范围内使用它。
但似乎这个表达式是有效的
if attached a.b as l_b and then attached l_b.c as l_c then
l_c.is_available_in_this_scope
l_b.is_available_in_this_scope
else
io.putstring ("you are wrong dear and either l_b and l_c are not available!")
end
虽然这个不是!
if attached a.b as l_b and then attached l_b.c as l_c
or attached a.x as l_b and then attached l_x.d as l_c then
l_c.is_available_in_this_scope -- Compiler complain about l_c
l_b.is_available_in_this_scope -- Compiler complain about l_b
else
io.putstring ("you are wrong dear and either l_b and l_c are not available!")
end
用我的代码
这编译
if attached {INTEGER_REF} field.item as l_int then
Result.put_integer (l_int.to_integer_64, primary_key_db_column_name)
elseif attached {INTEGER_64} field.item as l_int then
Result.put_integer (l_int, primary_key_db_column_name)
elseif attached {TUPLE} field.item as l_tuple and then attached {INTEGER_64} l_tuple.item (1) as l_int then
Result.put_integer (l_int, primary_key_db_column_name)
elseif attached {STRING} field.item as l_s then
Result.put_string (l_s, primary_key_db_column_name)
else
logger.write_error ("to_json-> Type not found in matching:" + field.item.out)
check
not_found_item_type: False
end
end
虽然这不是
if attached {INTEGER_REF} field.item as l_int then
Result.put_integer (l_int.to_integer_64, primary_key_db_column_name)
elseif attached {INTEGER_64} field.item as l_int
or attached {TUPLE} field.item as l_tuple and then attached {INTEGER_64} l_tuple.item (1) as l_int then
Result.put_integer (l_int, primary_key_db_column_name) -- Unknown identifier `l_int`
elseif attached {STRING} field.item as l_s then
Result.put_string (l_s, primary_key_db_column_name)
else
logger.write_error ("to_json-> Type not found in matching:" + field.item.out)
check
not_found_item_type: False
end
end
解决方案
对象测试有范围。用 表示对象测试OT
,其范围为
if OT then A else B end
if OT and ... then A else B end
if OT or ... then C else B end
只是A
。因此,对于析取,范围是空的,并且您不能在任何分支中使用相应的对象测试本地。
如果条件中有两个对象测试,它们的范围可能重叠或不重叠:
if OT1 and OT2 then A else B end
if OT1 and then OT2 then A else B end
if OT1 or OT2 then C else B end
在这里,和以前一样,对象测试局部变量的OT1
范围是A
。此外,对于and then
,范围包括OT2
,特别是OT2
可以使用 的局部OT1
。出于同样的原因,OT2
不能使用相同的对象 test local OT1
。
对于析取,对象测试局部变量的范围OT1
和OT2
都是空的。为了提供更多信息,具有助记符名称的相同代码如下所示:
if attached e1 as x and attached e2_without_x as y then use_x_and_y else B end
if attached e1 as x and then attached e2_with_x as y then use_x_and_y else B end
if attached e1 as x or attached e2_without_x as y then no_x_no_y else B end
如果所有涉及的表达式的类型相同,仍然可以仅使用一个第一个分支重写示例(情况并非如此,因为存在类型INTEGER_64
和INTEGER_REF
):
if attached
if attached {INTEGER_64_REF} field.item as i then
i
elseif
attached {TUPLE} field.item as t and then
t.count > 0 and then
attached {INTEGER_64_REF} t.item (1) as i
then
i
else
Void
end
as j
then
-- Use j
...
但这变得太麻烦了,使用多个分支或临时局部变量看起来是一个更好的选择。
推荐阅读
- json - 将列表转换为 Json
- python - AWS s3,拉姆达。您如何从具有前缀的 tmp 下载图像?
- moodle - 是否有 Web 服务 API 功能来获取 Moodle 中的类别注册?
- javascript - 如何在 sequelize 中将右外连接与 where 子句一起使用
- rust - Rust 自定义裸机编译目标:链接器需要“_start”符号并丢弃未使用的符号:如何指定自定义条目符号?
- node.js - 如何使用 Outlook api 发送 ejs
- python - Tabula-py 无法正确识别列
- apache - 安装密钥时 Apache2 语法错误 ssl
- asp.net-core - Blazor WebAssembly 中的用户管理
- testing - 端到端测试与移动应用程序交互的 Web 应用程序的最佳方法是什么