add draft for load arg handling

examples/loadsave.scri

@@ -1,2 +1,2 @@
-load :1;
+load :0;
 quicksave;

examples/middle_echo.scri

@@ -1,3 +1,3 @@
-load :1;
+load :0;
 echo 3 0 1 0.2;
 quicksave;

scritcher/error.py

@@ -0,0 +1,2 @@
+class InterpreterError(Exception):
+    pass

scritcher/executer.py

@@ -1,18 +1,20 @@
+import sys
 import shlex
-
+from .utils import load_file_path
-
+from .error import InterpreterError
-class InterpreterError(Exception):
-    pass
 
 
 class Interpreter:
     """Interpreter for scritcher instructions/statements."""
     def __init__(self):
-        pass
+        self.loaded_path = None
 
     def _cmd_noop(self):
         pass
 
+    def _cmd_load(self, loadpath: str):
+        path = load_file_path(loadpath)
+
     def run(self, line: str):
         """Run a single line."""
         print(f'running {line!r}')
@@ -20,6 +22,9 @@ class Interpreter:
         args = shlex.split(line)
         command = args[0]
 
+        if command != 'load' and self.loaded_path is None:
+            print('warn: no file loaded.')
+
         try:
             method = getattr(self, f'_cmd_{command}')
         except AttributeError:

scritcher/main.py

@@ -1,7 +1,8 @@
 import sys
 from pathlib import Path
 
-from .executer import Interpreter, InterpreterError
+from .executer import Interpreter
+from .error import InterpreterError
 
 def main():
     try:

scritcher/utils.py

@@ -0,0 +1,15 @@
+import sys
+from pathlib import Path
+from .error import InterpreterError
+
+def load_file_path(arg: str) -> Path:
+    """load given argument."""
+
+    try:
+        index = int(arg.split(':')[1])
+    except ValueError:
+        raise InterpreterError('Invalid argument index')
+    except IndexError:
+        return Path(arg).resolve()
+
+    return Path(sys.argv[2 + index])