  We investigate the observed spectrum of cosmic-ray electrons and positrons
from astrophysical sources, especially pulsars, and the physical processes for
making the spectrum spiky or smooth via continuous and multiple
electron/positron injections. We find that (1) the average electron spectrum
predicted from nearby pulsars are consistent with PAMELA, Fermi and H.E.S.S.
data. However, the ATIC/PPB-BETS peak around 500GeV is hard to produce by the
sum of multiple pulsar contributions and requires a single (or a few) energetic
pulsar(s). (2) A continuous injection produces a broad peak and a high energy
tail above the peak, which can constrain the source duration ($\lesssim 10^5$yr
with the current data). (3) The H.E.S.S. data in the TeV range suggest that
young sources with age less than $\sim 6 \times 10^4$yr are less energetic than
$\sim 10^{48}{\rm erg}$. (4) We also expect a large dispersion in the TeV
spectrum due to the small number of sources, that may cause the high energy
cutoff inferred by H.E.S.S. and potentially provide a smoking-gun for the
astrophysical origin. These spectral diagnostics can be refined in the near
future by the CALET experiments to discriminate different astrophysical and
dark matter origins.
