Add better messaging for nameof wierd calls.

Author: pwwang

README.md

@@ -10,8 +10,7 @@ Dark magics about variable names in python
 
 ## Installation
 ```shell
-pip install python-varname # will be deprecated after 0.4.0
-pip install varname # use this instead
+pip install varname
 ```
 
 ## Features
@@ -44,7 +43,7 @@ Thanks goes to these awesome people/projects:
   </tr>
 </table>
 
-Special thanks to @HanyuuLu to give up the name `varname` in pypi for this project.
+Special thanks to [@HanyuuLu][2] to give up the name `varname` in pypi for this project.
 
 ## Usage
 
@@ -255,6 +254,7 @@ For example:
 - `R` with `reticulate`.
 
 [1]: https://github.com/pwwang/python-varname
+[2]: https://github.com/HanyuuLu
 [3]: https://img.shields.io/pypi/v/varname?style=flat-square
 [4]: https://pypi.org/project/varname/
 [5]: https://img.shields.io/github/tag/pwwang/python-varname?style=flat-square

tests/test_varname.py

@@ -2,6 +2,7 @@
 import unittest
 
 import pytest
+import subprocess
 from varname import (varname,
                      VarnameRetrievingError,
                      Wrapper,
@@ -646,6 +647,19 @@ def test_nameof_full():
     # we are not able to retreive full names without source code available
     with pytest.raises(
             VarnameRetrievingError,
-            match='Did you call nameof in a weird way'
+            match='Are you trying to call nameof from evaluation'
     ):
         eval('nameof(a.b.c, full=True)')
+
+def test_nameof_from_stdin():
+    code = ('from varname import nameof; '
+            'x = lambda: 0; '
+            'x.y = x; '
+            'print(nameof(x.y, full=True))')
+    p = subprocess.Popen([sys.executable],
+                         stdin=subprocess.PIPE,
+                         stdout=subprocess.PIPE,
+                         stderr=subprocess.STDOUT,
+                         encoding='utf8')
+    out, _ = p.communicate(input=code)
+    assert 'Are you trying to call nameof in REPL/python shell' in out

varname.py

@@ -283,8 +283,8 @@ class Wrapper:
     """
 
     def __init__(self, value: Any, raise_exc: bool = True):
-        self.name: str = varname(raise_exc=raise_exc)
-        self.value: Any = value
+        self.name = varname(raise_exc=raise_exc)
+        self.value = value
 
     def __str__(self) -> str:
         return repr(self.value)
@@ -310,11 +310,11 @@ def _get_node(caller: int, raise_exc: bool = True) -> Optional[NodeType]:
     When the node can not be retrieved, try to return the first statement.
     """
     try:
-        frame: FrameType = _get_frame(caller + 2)
+        frame = _get_frame(caller + 2)
     except VarnameRetrievingError:
         return None
 
-    exet: executing.Executing = executing.Source.executing(frame)
+    exet = executing.Source.executing(frame)
 
     if exet.node:
         return exet.node
@@ -354,12 +354,19 @@ def _node_name(node: NodeType) -> str:
 
 def _bytecode_nameof(caller: int = 1) -> str:
     """Bytecode version of nameof as a fallback"""
-    frame: FrameType = _get_frame(caller)
-    return _bytecode_nameof_cached(frame.f_code, frame.f_lasti)
+    frame = _get_frame(caller)
+    source = frame.f_code.co_filename
+    return _bytecode_nameof_cached(frame.f_code, frame.f_lasti, source)
 
 @lru_cache()
-def _bytecode_nameof_cached(code: CodeType, offset: int) -> str:
-    """Cached Bytecode version of nameof"""
+def _bytecode_nameof_cached(code: CodeType, offset: int, source: str) -> str:
+    """Cached Bytecode version of nameof
+
+    We are trying this version only when the soucecode is unavisible. In most
+    cases, this will happen when user is trying to run a script in REPL/
+    python shell, with `eval`, or other circumstances where the code is
+    manipulated to run but sourcecode is not available.
+    """
     instructions = list(dis.get_instructions(code))
     (current_instruction_index, current_instruction), = (
         (index, instruction)
@@ -368,11 +375,19 @@ def _bytecode_nameof_cached(code: CodeType, offset: int) -> str:
     )
 
     if current_instruction.opname not in ("CALL_FUNCTION", "CALL_METHOD"):
-        raise VarnameRetrievingError(
-            "Did you call nameof in a weird way? "
-            "Without soucecode available, nameof can only retrieve the name of "
-            "a single variable without any keyword arguments being passed in."
-        )
+        if source == '<stdin>':
+            raise VarnameRetrievingError(
+                "Are you trying to call nameof in REPL/python shell? "
+                "In such a case, nameof can only be called with single "
+                "argument and no keyword arguments."
+            )
+        if source == '<string>':
+            raise VarnameRetrievingError(
+                "Are you trying to call nameof from evaluation? "
+                "In such a case, nameof can only be called with single "
+                "argument and no keyword arguments."
+            )
+        raise VarnameRetrievingError("Did you call nameof in a weird way? ")
 
     name_instruction = instructions[
         current_instruction_index - 1