Support for modulo and remainders, capacity planning, etc. CLoses #127

.github/workflows/python.yml

@@ -18,7 +18,7 @@ jobs:
         uses: actions/checkout@v6.0.2
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6.2.0
         with:
           python-version: ${{ matrix.python-version }}
           cache: 'pip'

CLAUDE.md

@@ -5,7 +5,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 ## Project Overview
 
-**bitmath** is a pure-Python library (no external runtime dependencies) for representing and converting file sizes across SI (decimal) and NIST (binary) unit systems. It supports arithmetic, rich comparisons, bitwise ops, parsing, formatting, and f-string/format() support.
+**bitmath** is a pure-Python library (no external runtime dependencies) for representing and converting file sizes across SI (decimal) and NIST (binary) unit systems. It supports arithmetic (including floor division, modulo, and `divmod` for capacity math), rich comparisons, bitwise ops, parsing, formatting, and f-string/format() support.
 
 ## Project Direction
 bitmath has been around for almost 12 years, and over that lifetime it promised to deliver backwards compatibility. It delivered on that promise and gathered a strong supporting of people and eventual "critical infrastructure" project status on the PyPI.org website.
@@ -20,7 +20,7 @@ Phases 1 (maintenance 1.4.0) and 2 (bitmath 2.0.0) are complete. The project:
 
 - Supports **Python 3.9 and newer only** (`requires-python = ">=3.9"` in `pyproject.toml`)
 - Uses `hatchling` as the build backend (replaces `setup.py`)
-- Uses `pytest` as the test runner (292 tests, 99% coverage — one branch in `system` property intentionally uncovered)
+- Uses `pytest` as the test runner (303 tests). Coverage is high but platform-sensitive: the `query_device_capacity` branches for the *other* OS are naturally uncovered on any single run.
 - Is published on PyPI as version 2.0.0
 - Drop-in compatible with the 1.x public API
 
@@ -71,5 +71,5 @@ All unit values are normalized to bits internally; conversion between units happ
 - Test runner: `pytest`
 - All tests are in `tests/` as `test_*.py` files
 - Test case names must be unique across the suite — enforced by `tests/test_unique_testcase_names.sh`
-- Coverage: 99% (one branch in `system` property intentionally uncovered)
+- Coverage is platform-sensitive: Windows and POSIX `query_device_capacity` paths only run on their respective OS
 - `unittest.mock` (stdlib) is used for patching in integration tests

NEWS.rst

@@ -142,13 +142,32 @@ still works exactly the same way. What 2.0.0 adds on top of that:
    NIST is the tiebreaker. Closes `issue #54
    <https://github.com/timlnx/bitmath/issues/54>`_.
 
+**Floor division, modulo, and divmod for capacity math**
+   bitmath objects now implement ``__floordiv__`` (``//``),
+   ``__mod__`` (``%``), and ``__divmod__`` — useful for
+   chunk-and-remainder capacity planning (*"how many N-sized chunks
+   fit into this device, and how much is left over?"*).
+   ``bm1 // bm2`` returns an ``int`` (count of whole divisions),
+   mirroring how ``bm1 / bm2`` returns a unitless ratio.
+   ``bm1 % bm2`` and ``divmod(bm1, bm2)`` return remainders as
+   bitmath objects of the **left-hand operand's type**, consistent
+   with every other bitmath arithmetic operator. The identity
+   ``(a // b) * b + (a % b) == a`` holds. See :ref:`capacity_math`
+   for worked examples including ``best_prefix()`` coercion and
+   ``bitmath.format`` context-manager integration.
+
 
 Project Infrastructure
 ======================
 
 The project infrastructure has been rebuilt to reflect how Python
 projects are actually maintained in 2026:
 
+**Project Security**
+   GitHub now has branch protection enabled. Releases are signed with
+   the maintainers `GPG key
+   <https://keys.openpgp.org/search?q=bitmath%40lnx.cx>`_.
+
 **Packaging**
    ``pyproject.toml`` with a hatchling backend replaces the old
    ``setup.py``/``setup.py.in`` template system. The package is

README.rst

@@ -46,6 +46,7 @@ focusing on file size unit conversion, functionality now includes:
 * Full NIST unit coverage including **ZiB**, **YiB**, **Zib**, and **Yib**
 * Automatic human-readable prefix selection (like in `hurry.filesize <https://pypi.python.org/pypi/hurry.filesize>`_)
 * Basic arithmetic operations (subtracting 42KiB from 50GiB)
+* Capacity math with floor division, modulo, and ``divmod`` (``GiB(1) // MiB(300)``, ``GiB(1) % MiB(300)``)
 * Rich comparison operations (``1024 Bytes == 1KiB``)
 * Bitwise operations (``<<``, ``>>``, ``&``, ``|``, ``^``)
 * Rounding via ``math.floor``, ``math.ceil``, and ``round``
@@ -207,6 +208,53 @@ Arithmetic
    2457.6
 
 
+Capacity Planning
+-----------------
+
+Floor division (``//``), modulo (``%``), and ``divmod()`` are handy for
+chunk-and-remainder capacity math. ``bm1 // bm2`` returns an ``int``
+(how many whole chunks fit); ``bm1 % bm2`` returns a ``bitmath`` of the
+**left-hand operand's type** (the leftover).
+
+.. code-block:: python
+
+   >>> from bitmath import GiB, MiB, TiB
+   >>> disk = GiB(1)
+   >>> chunk = MiB(300)
+
+   >>> disk // chunk        # how many whole 300 MiB chunks fit?
+   3
+   >>> disk % chunk         # leftover, typed as the LHS (GiB)
+   GiB(0.12109375)
+   >>> divmod(disk, chunk)  # both at once
+   (3, GiB(0.12109375))
+
+Re-express the remainder in a human-readable unit with
+``best_prefix()`` (or coerce directly with ``to_MiB()``, etc.):
+
+.. code-block:: python
+
+   >>> (GiB(1) % MiB(300)).best_prefix()
+   MiB(124.0)
+
+Pair with the ``bitmath.format`` context manager for clean reporting
+across a block of capacity calculations:
+
+.. code-block:: python
+
+   >>> import bitmath
+   >>> volume = TiB(1)
+   >>> block = GiB(7)
+   >>> with bitmath.format(fmt_str="{value:.2f} {unit}", bestprefix=True):
+   ...     whole, leftover = divmod(volume, block)
+   ...     print(f"{whole} whole blocks of {block} fit in {volume}")
+   ...     print(f"leftover: {leftover}")
+   146 whole blocks of 7.00 GiB fit in 1.00 TiB
+   leftover: 2.00 GiB
+
+The identity ``(a // b) * b + (a % b) == a`` holds, so ``divmod`` round-trips.
+
+
 Convert Units
 -------------
 

bitmath/__init__.py

@@ -858,17 +858,40 @@ def __truediv__(self, other):
             # bm1 / bm2
             return self._byte_value / float(other.bytes)
 
-    # def __floordiv__(self, other):
-    #     return NotImplemented
+    def __floordiv__(self, other):
+        """Floor division: Supported operations with result types:
 
-    # def __mod__(self, other):
-    #     return NotImplemented
+- bm1 // bm2 = int (whole divisions, unitless — mirrors bm1 / bm2 returning a ratio)
+- bm // num  = bm (LHS type)
+"""
+        if isinstance(other, numbers.Number):
+            # bm // num
+            result = self._byte_value // other
+            return (type(self))(bytes=result)
+        else:
+            # bm1 // bm2
+            return int(self._byte_value // other.bytes)
 
-    # def __divmod__(self, other):
-    #     return NotImplemented
+    def __mod__(self, other):
+        """Modulo (remainder): Supported operations with result types:
 
-    # def __pow__(self, other, modulo=None):
-    #     return NotImplemented
+- bm1 % bm2 = bm (LHS type) — remainder after floor-dividing bm1 by bm2
+- bm % num  = bm (LHS type)
+"""
+        if isinstance(other, numbers.Number):
+            # bm % num
+            result = self._byte_value % other
+            return (type(self))(bytes=result)
+        else:
+            # bm1 % bm2
+            return (type(self))(bytes=self._byte_value % other.bytes)
+
+    def __divmod__(self, other):
+        """divmod(bm, other) == (bm // other, bm % other).
+
+Result types match __floordiv__ and __mod__.
+"""
+        return (self.__floordiv__(other), self.__mod__(other))
 
     ##################################################################
 

docsite/source/index.rst

@@ -40,6 +40,7 @@ focusing on file size unit conversion, functionality now includes:
 * Full NIST unit coverage including **ZiB**, **YiB**, **Zib**, and **Yib**
 * Automatic human-readable prefix selection (like in `hurry.filesize <https://pypi.python.org/pypi/hurry.filesize>`_)
 * Basic arithmetic operations (subtracting 42KiB from 50GiB)
+* Capacity math with floor division, modulo, and ``divmod`` (``GiB(1) // MiB(300)``, ``GiB(1) % MiB(300)``)
 * Rich comparison operations (``1024 Bytes == 1KiB``)
 * Bitwise operations (``<<``, ``>>``, ``&``, ``|``, ``^``)
 * Rounding via :py:func:`math.floor`, :py:func:`math.ceil`, and :py:func:`round`
@@ -152,6 +153,53 @@ Arithmetic
    2457.6
 
 
+Capacity Planning
+-----------------
+
+Floor division (``//``), modulo (``%``), and ``divmod()`` are handy for
+chunk-and-remainder capacity math. ``bm1 // bm2`` returns an ``int``
+(how many whole chunks fit); ``bm1 % bm2`` returns a ``bitmath`` of the
+**left-hand operand's type** (the leftover).
+
+.. code-block:: python
+
+   >>> from bitmath import GiB, MiB, TiB
+   >>> disk = GiB(1)
+   >>> chunk = MiB(300)
+
+   >>> disk // chunk        # how many whole 300 MiB chunks fit?
+   3
+   >>> disk % chunk         # leftover, typed as the LHS (GiB)
+   GiB(0.12109375)
+   >>> divmod(disk, chunk)  # both at once
+   (3, GiB(0.12109375))
+
+Re-express the remainder in a human-readable unit with
+``best_prefix()`` (or coerce directly with ``to_MiB()``, etc.):
+
+.. code-block:: python
+
+   >>> (GiB(1) % MiB(300)).best_prefix()
+   MiB(124.0)
+
+Pair with the ``bitmath.format`` context manager for clean reporting
+across a block of capacity calculations:
+
+.. code-block:: python
+
+   >>> import bitmath
+   >>> volume = TiB(1)
+   >>> block = GiB(7)
+   >>> with bitmath.format(fmt_str="{value:.2f} {unit}", bestprefix=True):
+   ...     whole, leftover = divmod(volume, block)
+   ...     print(f"{whole} whole blocks of {block} fit in {volume}")
+   ...     print(f"leftover: {leftover}")
+   146 whole blocks of 7.00 GiB fit in 1.00 TiB
+   leftover: 2.00 GiB
+
+The identity ``(a // b) * b + (a % b) == a`` holds, so ``divmod`` round-trips.
+
+
 Convert Units
 -------------
 

docsite/source/index.rst.in

@@ -40,6 +40,7 @@ focusing on file size unit conversion, functionality now includes:
 * Full NIST unit coverage including **ZiB**, **YiB**, **Zib**, and **Yib**
 * Automatic human-readable prefix selection (like in `hurry.filesize <https://pypi.python.org/pypi/hurry.filesize>`_)
 * Basic arithmetic operations (subtracting 42KiB from 50GiB)
+* Capacity math with floor division, modulo, and ``divmod`` (``GiB(1) // MiB(300)``, ``GiB(1) % MiB(300)``)
 * Rich comparison operations (``1024 Bytes == 1KiB``)
 * Bitwise operations (``<<``, ``>>``, ``&``, ``|``, ``^``)
 * Rounding via :py:func:`math.floor`, :py:func:`math.ceil`, and :py:func:`round`