Make Truncating Configurable

check50/__init__.py

@@ -47,7 +47,9 @@ def _setup_translation():
 
 from . import regex
 from .runner import check
+from .config import config
 from pexpect import EOF
 
 __all__ = ["import_checks", "data", "exists", "hash", "include", "regex",
-           "run", "log", "Failure", "Mismatch", "Missing", "check", "EOF"]
+           "run", "log", "Failure", "Mismatch", "Missing", "check", "EOF",
+           "config"]

check50/_api.py

@@ -11,6 +11,7 @@
 from pexpect.exceptions import EOF, TIMEOUT
 
 from . import internal, regex
+from .config import config
 
 _log = []
 internal.register.before_every(_log.clear)
@@ -499,7 +500,7 @@ def wrapper(*args, **kwargs):
         return wrapper
     return decorator
 
-def _truncate(s, other, max_len=10):
+def _truncate(s, other):
     def normalize(obj):
         if isinstance(obj, list):
             return "\n".join(map(str, obj))
@@ -508,6 +509,11 @@ def normalize(obj):
 
     s, other = normalize(s), normalize(other)
 
+    if not config.dynamic_truncate:
+        if len(s) > config.truncate_len:
+            s = s[:config.truncate_len] + "..."
+        return s
+
     # find the index of first difference
     limit = min(len(s), len(other))
     i = limit
@@ -517,8 +523,8 @@ def normalize(obj):
             break
 
     # center around diff
-    start = max(i - (max_len // 2), 0)
-    end = min(start + max_len, len(s))
+    start = max(i - (config.truncate_len // 2), 0)
+    end = min(start + config.truncate_len, len(s))
 
     snippet = s[start:end]
 

check50/config.py

@@ -0,0 +1,69 @@
+class Config:
+    """
+    Configuration for `check50` behavior.
+
+    This class stores user-defined configuration options that influence
+    check50's output formatting.
+
+    For developers of `check50`, you can extend the `Config` class by adding new
+    variables to the `__init__`, which will automatically generate new "setter"
+    functions to modify the default values. Additionally, if the new
+    configuration needs to be validated before the user can modify it, add your
+    validation into the `_validators` dictionary.
+    """
+
+    def __init__(self):
+        self.truncate_len = 10
+        self.dynamic_truncate = True
+
+        # Create boolean validators for your variables here (if needed):
+        # A help message is not required.
+        self._validators = {
+            "truncate_len": (lambda val: isinstance(val, int) and val >= 1,
+                             "truncate_len must be a positive integer"),
+            "dynamic_truncate": (lambda val: isinstance(val, bool) or val in (0, 1),
+                                 "dynamic_truncate must be a boolean")
+        }
+
+        # Dynamically generates setter functions based on variable names and
+        # the type of the default values
+        self._generate_setters()
+
+    def _generate_setters(self):
+        def make_setter(attr):
+            """Factory for making functions like `set_<attr_name>(arg)`"""
+
+            def setter(self, value):
+                # Get the entry in the dict of validators.
+                # Check to see if the value passes the validator, and if it
+                # didn't, display the help message, if any.
+                validator_entry = self._validators.get(attr)
+
+                if validator_entry:
+                    if isinstance(validator_entry, tuple):
+                        validator, help = validator_entry
+                    else:
+                        validator, help = validator_entry, None
+
+                    if not validator(value):
+                        error_msg = f"invalid value for {attr}: {value}"
+                        if help:
+                            error_msg += f", {help}"
+                        raise ValueError(error_msg)
+
+                setattr(self, attr, value)
+            return setter
+
+        # Iterate through the names of every instantiated variable
+        for attribute_name in self.__dict__:
+            if attribute_name.startswith('_'):
+                continue  # skip "private" attributes (denoted with a prefix `_`)
+            value = getattr(self, attribute_name)
+            if callable(value):
+                continue  # skip functions/methods
+
+            # Create a class method with the given name and function
+            setattr(self.__class__, f"set_{attribute_name}", make_setter(attribute_name))
+
+
+config = Config()