Defer loading element data until attribute access

mendeleev/__init__.py

@@ -4,4 +4,152 @@
 
 from .mendeleev import *  # noqa F403
 from .models import *  # noqa F403
-from .elements import *  # noqa F403
+
+_symbols = [
+    "H",
+    "He",
+    "Li",
+    "Be",
+    "B",
+    "C",
+    "N",
+    "O",
+    "F",
+    "Ne",
+    "Na",
+    "Mg",
+    "Al",
+    "Si",
+    "P",
+    "S",
+    "Cl",
+    "Ar",
+    "K",
+    "Ca",
+    "Sc",
+    "Ti",
+    "V",
+    "Cr",
+    "Mn",
+    "Fe",
+    "Co",
+    "Ni",
+    "Cu",
+    "Zn",
+    "Ga",
+    "Ge",
+    "As",
+    "Se",
+    "Br",
+    "Kr",
+    "Rb",
+    "Sr",
+    "Y",
+    "Zr",
+    "Nb",
+    "Mo",
+    "Tc",
+    "Ru",
+    "Rh",
+    "Pd",
+    "Ag",
+    "Cd",
+    "In",
+    "Sn",
+    "Sb",
+    "Te",
+    "I",
+    "Xe",
+    "Cs",
+    "Ba",
+    "La",
+    "Ce",
+    "Pr",
+    "Nd",
+    "Pm",
+    "Sm",
+    "Eu",
+    "Gd",
+    "Tb",
+    "Dy",
+    "Ho",
+    "Er",
+    "Tm",
+    "Yb",
+    "Lu",
+    "Hf",
+    "Ta",
+    "W",
+    "Re",
+    "Os",
+    "Ir",
+    "Pt",
+    "Au",
+    "Hg",
+    "Tl",
+    "Pb",
+    "Bi",
+    "Po",
+    "At",
+    "Rn",
+    "Fr",
+    "Ra",
+    "Ac",
+    "Th",
+    "Pa",
+    "U",
+    "Np",
+    "Pu",
+    "Am",
+    "Cm",
+    "Bk",
+    "Cf",
+    "Es",
+    "Fm",
+    "Md",
+    "No",
+    "Lr",
+    "Rf",
+    "Db",
+    "Sg",
+    "Bh",
+    "Hs",
+    "Mt",
+    "Ds",
+    "Rg",
+    "Cn",
+    "Nh",
+    "Fl",
+    "Mc",
+    "Lv",
+    "Ts",
+    "Og",
+]
+
+
+def __getattr__(name):
+    """
+    Dynamically creates an element object and stores it in the module's namespace.
+
+    Args:
+        name (str): The symbol of the element to be created.
+
+    Returns:
+        Element: The element object corresponding to the provided symbol.
+
+    Raises:
+        ImportError: If the element symbol is not found in _symbols.
+
+    Examples:
+        Usage:
+        >>> from mendeleev import C
+        >>> print(C.atomic_number)
+        6
+    """
+    if name in _symbols:
+        element_obj = element(name)  # noqa: F405
+        globals()[name] = element_obj
+        return element_obj
+    raise ImportError(
+        f"module 'mendeleev' has no element with symbol '{name}', please check you spelling"
+    )